Moist & buttery yellow cake recipe from scratch! A true classic with chocolate buttercream, this easy recipe is made from basic pantry staples.
Place the cake flour, all-purpose flour, sugar, baking powder, baking soda, and salt in the bowl of an electric mixer, and stir on low speed to combine.
Add the butter, mixing on medium-low speed until the mixture resembles damp sand (about 1 minute).
Mix in the eggs and the additional yolk until fully incorporated.
Scrape the bottom and sides of the bowl with a silicone spatula, then add the sour cream, milk, and vanilla.
Mix on medium speed for 2 to 3 minutes, to aerate the batter and build the cake's structure.
Divide the batter equally between the prepared pans, and bake until the edges are golden brown, the cake feels springy when pressed, and a toothpick inserted in the thickest partcomes out clean (approximately 35 to 45 minutes).
Cool completely before filling and frosting.
Place the butter, salt, and cocoa powder in a large mixing bowl, and add about 1/3 of the powdered sugar.
With an electric mixer, beat on medium speed until combined.
Add the remaining powdered sugar (in 2 more additions), beating until combined.
Stir in the cream** and vanilla, then turn the mixer up to medium-high speed and whip the frosting until light and fluffy.
**The amount of cream needed can vary. Start with 3 tablespoons and add more if necessary. You just want it to have a nice spreadable consistency, without being too loose or runny.
For more info on the frosting recipe, click here: Easy Chocolate Frosting.