In a separate bowl, whisk together the buttermilk, sour cream, oil, egg, and vanilla until fully combined. Then add red food coloring.
80 grams buttermilk, 54 grams sour cream, 62 grams vegetable oil, 1 large egg, 1 teaspoon vanilla extract, 1 teaspoon red gel food coloring
Gradually whisk the wet ingredients into the flour mixture. Scrape the sides and bottom of the bowl. Mix until the dry streaks just disappear.
Pour the cake batter into the prepared pan. Bake for 24-30 minutes until a toothpick inserted in the center comes out clean.
Remove the cake from the oven. Let cool in the hot pan for 5-10 minutes, then transfer it to a wire cooling rack. Cool completely for 1 hour before frosting.
Cream Cheese Frosting
Beat softened butter and cream cheese together in the bowl of a stand mixer or electric mixer on medium-high speed until smooth and creamy.
Scrape down the sides of the bowl. Gradually mix in the powdered sugar on low speed in two additions.
160 grams powdered sugar
Add the vanilla, then increase to medium speed until light and fluffy.
¼ teaspoon vanilla extract
Assembly
Once completely cool, use a serrated knife to cut two angled pieces that will end up being the bottom of the heart.
Trim the two angled pieces if needed, using a serrated knife to round them out. Add frosting to the top of the heart and attach the pieces.
Pipe a border of cream cheese frosting on top, then fill in the center. Decorate with sprinkles, then slice and enjoy!
Notes
Use room temperature ingredients for a smooth batter and frosting.You can bake the cake in a heart-shaped pan or leave it round instead of shaping into a heart.Storage- Store the cake in an airtight container in the fridge for up to 3 days. Warm on the counter for 30 minutes before serving so the frosting gets soft.Freezing- Wrap the whole cake or individual slices it in plastic wrap and then aluminum foil. Freeze for up to 3 months. Thaw in the fridge overnight before serving.