This lemon chocolate cake is a 6-inch cake with 3 layers of super soft, moist chocolate sponge. It's filled with tart lemon curd and frosted with tangy, silky smooth lemon Swiss meringue buttercream. This unique flavor combination is sure to impress all the chocolate and lemon lovers in your life!
Today, I'm excited to share a recipe that combines two of my absolute favorite flavors: lemon and chocolate. That's right, we're talking about a lemon chocolate cake! I know it's a unique combination and might sound weird at first, but trust me when I say it's a match made in heaven.
This cake is the perfect balance of sweet and tangy, with a rich chocolatey sponge that will have you coming back for more. It's filled with tangy lemon curd and frosted with silky smooth lemon Swiss meringue buttercream. Whether you're a fan of lemon desserts, chocolate desserts, or both, this cake is sure to satisfy your sweet tooth.
Here are some notes about the ingredients used. For quantities and the full ingredient list, see the recipe card below.
Ingredients for the Cake
- All purpose flour- I usually use cake flour in my vanilla cakes to make them light and airy, but I love using AP flour in chocolate cakes to make them a little more hearty, moist, and slightly dense.
- Granulated sugar- White sugar sweetens the cake batter, retains moisture, and mixes in smoothly.
- Cocoa powder- I prefer the chocolatey depth of Dutch-processed cocoa powder. This cocoa powder is treated with alkali, making it less acidic with a richer flavor and color. Unsweetened (or natural) cocoa powder works too if you don't have Dutch-processed.
- Baking powder & baking soda- These two leaveners work together to give the cake a fluffy texture while keeping it dense and moist. They're essential for helping the cake rise to perfection.
- Salt- Cakes need salt so they're not cloyingly sweet. Use finely ground sea salt, Kosher salt, or pink Himalayan salt. If your salt is coarse, add an extra ¼ teaspoon.
- Egg and egg white- An egg binds the ingredients together and an egg white gives the sponge extra lift. Make sure they're at room temperature; take them out of the refrigerator an hour before you start.
- Oil- I love using oil in chocolate cakes instead of butter to make them extra moist and spongey. You can use any neutral oil, like vegetable, avocado, grapeseed, or canola oil.
- Buttermilk- If you've made my recipes, you know I'm a huge buttermilk fan. It thins out the batter, adds a tangy flavor, and tenderizes the gluten. It almost guarantees a soft, fluffy cake!
- Vanilla extract- This enhances the chocolate flavor and gives the cake a lovely aroma.
- Brewed coffee- Coffee brings out the chocolate flavor, making it richer and deeper. Use hot coffee to activate (or bloom) the cocoa powder.
- Lemon curd- Lemon curd is used to fill the cake! You can follow whatever homemade lemon curd recipe you like (I suggest my eggless lemon curd, it's so delicious in my lemon bar cookies) or buy it at the grocery store.
Ingredients for the Buttercream
- Pasteurized egg whites- We're making Swiss meringue buttercream the easy way- with pasteurized egg whites! These have been heat treated to kill harmful bacteria, making them safe to eat. Using pasteurized egg whites eliminates the need to heat them over a double boiler like you would in a traditional Swiss Meringue buttercream recipe. Look for them in the egg section at your grocery store and make sure the box says "pasteurized." Take them out of the refrigerator 30 minutes before making the frosting so they reach room temperature and are easier to whip up.
- Powdered sugar- By using powdered sugar, there's no need to dissolve granulated sugar in hot egg whites. You don't have to worry about sifting it either.
- Unsalted butter- When it comes to making buttercream, using unsalted butter gives you more control over the flavor. Make sure your butter is softened and at room temperature before you start mixing. If you use cold butter, your buttercream will curdle and nobody wants that! Take it out of the fridge at least an hour before you start for it to soften up.
- Lemon juice- Fresh lemon juice adds tangy lemon flavor to the frosting. Don't use the bottled stuff because the flavor won't be as tart.
- All purpose flour: To make this cake gluten free, use Bob's Red Mill 1-to-1 Baking Flour.
- Buttermilk: You can substitute plain kefir, plain Greek yogurt, or sour cream for buttermilk at a 1:1 ratio. You can even make your own buttermilk by combining 1 cup of whole milk with 1 tablespoon of either vinegar or lemon juice. Just let the mixture sit for about 10 minutes and it's ready to use.
- Brewed coffee: If you don't have coffee, use hot water. The chocolate flavor won't be as deep, but you'll still have delicious cake in the end!
Helpful Equipment & Tools
- I recommend using 6 inch round metal pans for this recipe. Glass or silicone pans can cause your cake to burn since they don't heat up evenly. If you have non-stick pans, even better! But if you don't, don't forget to spray them with non-stick baking spray before lining with parchment rounds.
- For making the buttercream, a 5-quart stand mixer with the wire whisk and paddle attachments is ideal. Make sure the bowl hold 5 quarts so powdered sugar doesn't fly out.
- To decorate your cake, an offset spatula is a must-have for getting that smooth, even look. A bench scraper is also super helpful for making everything look polished and professional.
- If you want to take your cake decorating skills to the next level, consider getting a revolving cake decorating stand with a non-slip pad. It's not necessary, but it definitely makes it easier to apply icing and other decorations evenly to the sides and top of your cake.
Step by Step Instructions
How to Make the Chocolate Cake
Before you start, preheat the oven to 350°F/180°C. Spray your 3 cake pans with baking spray if needed and line them with parchment paper.
STEP 1: First, add the flour, sugar, cocoa powder, baking powder, baking soda, and salt to a large mixing bowl. Whisk them together until well combined.
STEP 2: In a separate large bowl, whisk the egg, egg white, oil, buttermilk, and vanilla extract together vigorously until smooth.
STEP 3: Now, pour the wet ingredients into the bowl of dry ingredients. Use a rubber spatula to fold everything together. When you start, there will be lots of lumps, but keep mixing until the batter drips off the spatula in smooth ribbons.
STEP 4: Pour half of the hot coffee into the cake batter and fold it in with your rubber spatula until smooth. Repeat with the other half. The batter will be very thin.
STEP 5: Pour the batter evenly between your 3 round cake pans. After that, place the pans in the middle rack of the oven and bake for 23-28 minutes or until a toothpick inserted in the center comes out clean with a few moist crumbs.
STEP 6: Remove the cakes from the oven and let them cool in their pans for about 20 minutes. Once 20 minutes are up, run a toothpick around the edges to release the cakes from the pans. Gently flip each cake on to a wire cooling rack and carefully lift up. These cakes are super soft and fragile, so be careful!
STEP 7: Let the layers cool to room temperature or pop them in the freezer for 20 minutes or so. Now you can start making the frosting.
How to Make the Lemon Frosting
STEP 1: Clean out and dry your stand mixer before fitting it with the wire whip attachment. If there's any fat or residue the eggs whites won't set up! Place the pasteurized egg whites and powdered sugar in the bowl and whisk them together on low for about 30 seconds.
STEP 2: Once the egg whites and powdered sugar are lightly mixed, crank up the speed to medium-high. Whip for 8-10 minutes until you have a thick, opaque white meringue. You'll know it's ready when you see peaks that stand up and curl on the ends.
STEP 3: Add the salt, mixing on medium low. Then, start adding in the softened butter bit by bit, scraping down the sides of the bowl as needed. Add 1 tablespoon of butter at a time, waiting for each addition to mix in before adding more.
STEP 4: Once all the butter is added, switch to the paddle attachment and gradually pour in your lemon juice. Lemon juice stabilizes egg whites, so pouring it in all at once with leave you with a rubbery looking mess. Keep mixing until the buttercream is smooth and tastes sweet and lemony- about 10 minutes.
Assembling the Cake
Before you start assembling the cake, prepare a piping bag with a large round tip and fill it half way with buttercream.
STEP 1: Use a serrated knife or cake leveler to level off the top of each cake layer to create a flat surface.
STEP 2: Add a tablespoon of frosting to the middle of your cake board or stand and fan it out with your offset spatula. This acts as the glue to keep the cake from sliding around. Next, place one cake layer on the board, flat side down.
STEP 3: Spread a thin layer of buttercream evenly across the cake. Then, pipe a thick ring of buttercream around the edge. This creates a barrier so no lemon curd spills out.
STEP 4: Spread an even layer of lemon curd inside the ring of buttercream. Be generous with the curd, but don't add so much that it seeps out.
STEP 5: Repeat the previous 2 steps with the second cake layer. After that, place the last layer of cake on top with the bottom side up. Gently press down with your hands to remove any air bubbles that could cause uneven sides.
Apply a thin layer of frosting all over the cake, using your offset spatula or bench scraper to smooth it out. This is called the "crumb coat" and it helps to lock in any crumbs so they don't mix with the final layer of frosting. For a semi-naked look, you can leave the cake as is, or you can add another layer of frosting after chilling the cake in the freezer for 20 minutes.
STEP 6: After the crumb coat is no longer sticky, it's time for the second layer of frosting. Apply a thick layer all over the cake, making sure to cover any gaps or uneven spots.
To decorate, use your bench scraper to smooth out the sides and edges. I piped dollops of frosting on top of the cake using a star tip, but you can use whatever decorating technique you like.
Top the cake with chocolate shavings, fresh fruit, whipped cream, or more lemon zest. Slice and enjoy!
Expert Baking Tips
- Don't overmix the batter. Overmixing the batter can make the cake tough and dense. Mix the ingredients until just combined.
- Use room temperature ingredients. Room temperature ingredients mix more easily and evenly. Let the eggs, butter, and buttermilk reach room temperature before using them.
- Use a kitchen scale. Weighing the ingredients in grams instead of using measuring cups ensures accuracy and consistent results. Metric measurements are provided in the recipe card below.
- Don't overbake. Check the cake a few minutes before the suggested baking time as oven temperatures can vary. The cake is done when a toothpick inserted in the center comes out clean.
- Chill the cake before decorating. Chilling the cake makes it easier to handle and prevents the frosting from melting.
Additions & Variations
Here are some extra ingredients you can add to your cake.
- Fresh berries: Serve the lemon chocolate cake with fresh berries like raspberries, blueberries, or strawberries for a burst of fruity flavor.
- Lemon or chocolate ganache: Drizzle a lemon or chocolate ganache over the cake for an extra layer of flavor and a beautiful presentation.
- Cream cheese frosting: Instead of Swiss meringue buttercream, add a little lemon juice to this cream cheese frosting recipe to frost the cake with.
- Whipped cream: Top the cake with whipped cream for a light and airy contrast to the rich chocolate.
- Candied lemons: Add some texture and sweetness by decorating the cake with candied lemon slices or lemon peel.
- Chopped nuts: Sprinkle some chopped pistachios, almonds, or hazelnuts on top of the frosting for a nutty crunch.
- Coconut: Toasted coconut flakes add a tropical twist to the cake and pair well with lemon and chocolate.
Storage & Freezing
Your frosted chocolate lemon cake will keep in the fridge for up to a week because the frosting seals in moisture. To keep it fresh, I recommend storing it in a cake carrier or other big airtight container. If you've already sliced into it, make sure to cover the cut section with some extra frosting so it doesn't dry out.
Store leftover frosting in an airtight container in the fridge for up to a week. When you're ready to use it again, give it a quick mix to soften and smooth it out.
Freeze individual cake slices by wrapping them snugly in plastic wrap and storing them in an airtight container. You can keep them in the freezer for up to three months. When you're ready to enjoy a slice, simply unwrap a slice and let it sit on a plate at room temperature for about an hour to thaw.
I wouldn't recommend freezing the whole uncut cake. However, one handy trick is to freeze the cake layers before frosting them. This way, you can break up the baking and decorating tasks, making everything much more manageable. Plus, frosting frozen cake layers tends to be easier because you'll have fewer loose crumbs to deal with.
Frequently Asked Questions
I don't recommend freezing leftover Swiss meringue buttercream on its own because the texture won't be the same. Egg whites tend to weep after they're frozen, so it's best to use the frosting up on the cake or not freeze it at all.
Yes! This recipe will make about 12 cupcakes. Baking them for the same amount of time should work, but keep an eye on them. Fill them with lemon curd after baking.
You can use 2 6" pans (the layers will be quite thick!), 2 8" pans, or a 9x13" cake pan.
More Cake Recipes to Try
Lemon Chocolate Cake
- 160 grams all purpose flour
- 300 grams granulated sugar
- 75 grams cocoa powder dutch-processed or natural
- 1 ½ teaspoon baking powder
- ¾ teaspoon baking soda
- ½ teaspoon salt
- 1 large egg room temperature
- 1 egg white room temperature
- 130 grams neutral oil
- 225 grams buttermilk
- 1 teaspoon vanilla extract
- 210 grams brewed coffee hot
- 150 grams lemon curd homemade or store-bought
Lemon Swiss Meringue Buttercream
- 113 grams pasteurized egg whites room temperature
- 453 grams powdered sugar
- ½ teaspoon salt
- 453 grams unsalted butter softened
- 115 grams lemon juice
- Preheat the oven to 350°F/180°C. Spray 3 cake pans with baking spray if needed and line with parchment paper.
- Add the flour, sugar, cocoa powder, baking powder, baking soda, and salt to a large mixing bowl and whisk together until combined.160 grams all purpose flour, 300 grams granulated sugar, 75 grams cocoa powder, 1 ½ teaspoon baking powder, ¾ teaspoon baking soda, ½ teaspoon salt
- In a separate large bowl, whisk the egg, egg white, oil, buttermilk, and vanilla extract until smooth.1 large egg, 1 egg white, 130 grams neutral oil, 225 grams buttermilk, 1 teaspoon vanilla extract
- Pour the wet ingredients into the dry ingredients. Fold until batter drips off the spatula in smooth ribbons.
- Pour half of the hot coffee into the batter and fold until smooth. Repeat with the other half. The batter will be very thin.210 grams brewed coffee
- Distribute the batter evenly between 3 cake pans. Bake for 23-28 minutes or until a toothpick inserted in the center comes out clean.
- Let the cakes cool in the pans for 20 minutes. Gently flip each cake on to a wire cooling rack and release the pan. Chill in the freezer for 20 minutes.
Lemon Swiss Meringue Buttercream
- Place pasteurized egg whites and powdered sugar in a 5-quart stand mixer bowl fitted with the wire whip attachment. Beat on low for 30 seconds.453 grams powdered sugar, 113 grams pasteurized egg whites
- Increase the speed to medium high and beat for 8-10 minutes until a thick white meringue forms.
- Turn the speed down to low and beat in the salt. Add the softened butter 1 tablespoon at a time. Mix on low for 10 minutes.½ teaspoon salt, 453 grams unsalted butter
- Switch to the paddle attachment and pour in the lemon juice 1 tablespoon at a time until well combined.115 grams lemon juice
- Level off the top of each cake layer to create a flat surface.
- Spread a small amount of frosting on the cake board. Place 1 layer of cake on top.
- Spread a thin layer of buttercream evenly across the cake. Pipe a thick ring of buttercream around the edge of the cake.
- Spread an even layer of lemon curd inside the ring of buttercream.150 grams lemon curd
- Place the second cake layer on top and repeat the previous 2 steps.
- Place the last layer of cake on top with the bottom facing up. Spread a very thin layer of frosting, or crumb coat, all over the cake. Freeze for 20 minutes to seal in crumbs.
- Spread a thick second layer of frosting all over the cake. Pipe with decorations, garnish with lemon slices or chocolate shavings, and enjoy.