This chocolate custard cake features a creamy chocolate custard filling sandwiched between two layers of ultra moist chocolate cake! It's frosted with silky chocolate Swiss meringue buttercream that's deeply chocolatey but not too sweet. This might be the best chocolate cake you'll ever make!
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Why You'll Love This Recipe
- There's rich chocolate flavor throughout the whole cake, from the ultra-moist chocolate layers to the creamy chocolate custard filling in the center. It's perfect for chocolate lovers and special occasions!
- The chocolate custard really sets this cake apart. It's smooth, silky, and deeply chocolatey, made on the stovetop for a texture similar to pastry cream. Nestled between the cake layers, it adds moisture and richness while keeping the cake balanced and not too sweet.
- The cake is finished with chocolate Swiss meringue buttercream, which is light, glossy, and far less sweet than traditional American buttercream. It spreads like a dream! I make mine using my faux Swiss meringue buttercream method, with pasteurized egg whites so you don't need a bain-marie. It's a great option if you don't decorate cakes often.
Ingredient Notes
- Egg yolks and granulated sugar make up the base of the custard filling. Make sure the yolks are room temperature. Cold eggs can be shocked when mixed with hot milk.
- Make sure to use good quality bittersweet or dark chocolate for the custard. These types of chocolate contain more cocoa solids, ensuring that the custard thickens properly. I always reach for Lindt or Ghirardelli.
- For the cake layers, I mixed hot coffee with unsweetened cocoa powder. This blooms the cocoa, releasing its full spectrum of flavor. You can use boiling water if you don't have coffee, but I love how coffee deepens the chocolate flavor (you can't taste the coffee at all).
- The wet ingredients for the cake include vegetable oil and large eggs. I love making chocolate cakes with oil instead of butter because it makes it extra moist!
- For even more moisture and acidity that creates a tender texture, we're adding buttermilk. Sour cream works too.
For assembling the cake:
- The cake layers are filled with the chocolate custard and frosted with my chocolate Swiss meringue buttercream. The buttercream is made with egg whites, granulated sugar, salted butter, cocoa powder, and vanilla.
For the full list of ingredients and measurements, see the recipe card below.
Expert Baking Tips
- Temper the egg yolks gradually. This is key for a smooth custard! Gradually whisk a small amount of the hot milk into the yolk mixture to gently raise its temperature, then add the warmed yolks back into the saucepan. The process is slow but worth it since it keeps the eggs from curdling.
- Cook the custard over medium-low heat. Also make sure to whisk constantly. The movement helps the mixture thicken evenly and smoothly while preventing it from sticking or burning on the bottom of the pan.
- Measure the flour correctly. Too much flour can make cakes dry and dense. For best results, use a kitchen scale to weigh the flour. If using measuring cups, gently spoon the flour into the cup and level it off without packing it down.
- To prevent the filling from leaking, pipe a thick, sturdy ring of frosting around the edge of the cake layer before adding the cream filling. Keep the filling away from the edges and make sure the frosting barrier is fully sealed so everything stays in place.
Step by Step Instructions
Step 1: For the chocolate custard, whisk the egg yolks and sugar together in a medium bowl. Then whisk in the cornstarch.
Step 2: Heat the milk, vanilla, and salt in a medium saucepan until it bubbles around the edges. Don't let it boil! Then slowly pour it into the egg mixture, whisking to temper the egg yolks.
Step 3: Return the custard to the pot, then add the chocolate. Whisk over medium-low heat, stirring until the chocolate melts and the mixture thickens and bubbles slightly, about 5-8 minutes.
Step 4: Take the pan off the stove, and pour the custard through a fine mesh sieve into a bowl to remove lumps. Cool to room temperature, then cover the bowl with plastic wrap and chill in the refrigerator while you make the cake layers.
Step 5: For the chocolate cake, preheat the oven to 350ยฐF and line two 8-inch round cake pans with parchment paper. Set aside, then whisk the dry ingredients together in a medium bowl.
Step 6: In a separate large bowl, whisk the oil, eggs, vanilla extract, and buttermilk together until well combined.
Step 7: Slowly fold in half the dry ingredients until mostly combined, then stir in half of the hot coffee. Make sure to scrape the sides and bottom of bowl. Repeat once more. The mixture should be thin.
Step 8: Evenly pour the cake batter into the prepared pans, then bake at 350ยฐF for 15-20 minutes or until toothpick inserted in the center comes out clean. Let cake layers cool in the hot pans for 10 minutes, then flip them on to a wire rack and cool completely before leveling and decorating.
Assembling the Cake
Step 9: First, level the cakes with a serrated knife or a cake leveler to get a smooth base. Then pipe a tall ring of buttercream on the outer edge of one cake layer. Spread a generous amount of custard inside.
Step 10: Top with second cake layer and spread a thin layer of frosting over the entire cake using an offset spatula. This is called the crumb coat because it locks in loose crumbs.
Step 11: Chill the cake in the fridge for about 20 minutes or until the frosting is dry to the touch, then spread a thick final coat all over the cake.
Step 12: Decorate the cake to your liking! I alternated between an open star piping tip and a closed star tip to pipe a border.
Storage
Because this of the custard in this chocolate custard cake, it should be stored in the refrigerator. Refrigerate in an airtight container for up to 4 days. Serve the cake at room temperature.
More Cake Recipes to Try
๐ Recipe
Chocolate Custard Cake
Equipment
- 1 Electric hand mixer or stand mixer
- 1 offset spatula
- 1 bench scraper
- 1 cake turntable optional
Need Metric or US Customary Measurements?
Use the buttons below to toggle between grams and cups!
Ingredients
Chocolate Custard
- 3 egg yolks room temperature
- 66 grams granulated sugar
- 2 tablespoons cornstarch
- 240 grams whole milk
- 1 teaspoon vanilla bean paste
- 56 grams bittersweet chocolate chopped, 2 ounces
Chocolate Cake
- 180 grams all purpose flour
- 300 grams granulated sugar
- 75 grams unsweetened cocoa powder
- 1 ยฝ teaspoon baking powder
- ยพ teaspoon baking soda
- ยฝ teaspoon salt
- 120 grams vegetable oil
- 2 large eggs room temperature
- 1 teaspoon vanilla extract
- 240 grams buttermilk room temperature
- 200 milliliters hot coffee
Chocolate Swiss Meringue Buttercream
- 113 grams pasteurized egg whites
- 450 grams powdered sugar
- 453 grams salted butter room temperature
- 56 grams cocoa powder
- 1 teaspoon vanilla extract
Instructions
Chocolate Custard
- Whisk the egg yolks and granulated together in a medium bowl until pale and smooth. Whisk in the cornstarch until fully dissolved.3 egg yolks, 66 grams granulated sugar, 2 tablespoons cornstarch
- Add the whole milk and vanilla to a medium saucepan. Whisk over medium heat until steaming and small bubbles form around the edges. Do not let it boil.240 grams whole milk, 1 teaspoon vanilla bean paste
- Pour the hot milk into the egg mixture a little at a time while whisking constantly to gently temper the yolks.
- Pour the custard mixture back into the saucepan and add the chocolate. Cook over medium-low heat, whisking constantly and scraping the bottom of the pan, until the chocolate completely melts and the custard thickens. It should gently bubble and coat the back of a spoon, about 5-8 minutes.56 grams bittersweet chocolate
- Remove the pan from the heat and immediately pour the custard through a fine-mesh sieve into a clean bowl to remove any lumps. Let cool to room temperature, then press plastic wrap directly onto the surface and refrigerate until chilled while you prepare the cake layers.
Chocolate Cake
- Preheat the oven to 350ยฐF. Line two 8-inch round cake pans with parchment paper and set aside.
- In a medium bowl, whisk together the all purpose flour, sugar, cocoa powder, baking powder, baking soda, and salt. Set aside.180 grams all purpose flour, 300 grams granulated sugar, 75 grams unsweetened cocoa powder, 1 ยฝ teaspoon baking powder, ยพ teaspoon baking soda, ยฝ teaspoon salt
- In a separate large bowl, whisk the oil, eggs, vanilla extract, and buttermilk until smooth and well combined.120 grams vegetable oil, 2 large eggs, 240 grams buttermilk, 1 teaspoon vanilla extract
- Fold in half of the dry ingredients until mostly incorporated, then slowly stir in half of the hot coffee, scraping the sides and bottom of the bowl. Repeat with the remaining dry ingredients and finish with the coffee. The batter will be thin.200 milliliters hot coffee
- Divide the batter evenly between the prepared pans. Bake for 15-20 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
- Let the cakes cool in the pans for 10 minutes, then turn out onto a wire rack and cool completely before leveling.
Chocolate Swiss Meringue Buttercream
- Place the egg whites and powdered sugar in the bowl of a 5-quart stand mixer. With the whisk attachment, beat the ingredients on low until combined.113 grams pasteurized egg whites, 450 grams powdered sugar
- Increase the speed to medium high and beat for 8-10 until a meringue forms. It should be thick and opaque with tips that stand up but bend at the ends. It is ok if your meringue doesn't stiffen all the way as long as it is thick and pure white.
- Turn the speed down to low and add the softened butter 1 tablespoon at a time, mixing on medium-low for about 10 minutes.453 grams salted butter
- Add the cocoa powder and vanilla extract. Mix on low until combined, then beat for about 1 minute on medium until smooth.56 grams cocoa powder, 1 teaspoon vanilla extract
Assembly
- Level the cake layers with a serrated knife or cake leveler if needed. Place one layer on a serving plate and pipe a tall ring of buttercream around the edge to create a barrier. Fill the center with a generous layer of chilled chocolate custard.
- Place the second cake layer on top. With your offset spatula, spread a thin, even layer of frosting over the entire cake to seal in crumbs.
- Freeze the cake for about 20 minutes, or until the frosting is dry to the touch. Finish with a thick, smooth coat of frosting.
- Decorate with frosting swirls and chocolate jimmies or chocolate shavings. Slice and enjoy!
Notes
- No buttermilk?ย You can use sour cream or plain Kefir instead!
- Storage:ย Wrap the entire cake tightly in plastic wrap or store it in a large airtight container, like a cake carrier. It keeps in the refrigerator for up to 5 days. Serve at room temperature.
- Freezing:ย Wrap the entire cake in plastic wrap and then a layer of aluminum foil. Freeze for up to 3 months. Thaw overnight in the refrigerator before serving. You can also wrap individual slices in plastic wrap and foil and freeze them in a large freezer bag.
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