1cup (226g)unsalted butter,softened to room temperature
2 ¼cups (486g)granulated sugar
4(220g)large eggs
2tsp (8g)vanilla extract
3cups (360g)cake flour,spooned and leveled
3 ½tsp (14g)baking powder
1tsp coarse Kosher salt(if using table salt, use half the amount)
1 ⅓cups (359ml)whole buttermilk
⅔cup (160g)full-fat sour cream
Buttercream
2cups (452g)unsalted butter,softened to room temperature
3 ¼cups (455g)powdered sugar
¾cup (62g)unsweetened cocoa powder
1tbsp (9g)meringue powder
¼tsp coarse Kosher salt(if using table salt, use half the amount)
2tsp (8g)vanilla extract
2-4tbsp (33-66ml)milk or cream,if needed
Instructions
Cake
Preheat the oven to 350 F. Prepare three 8-inch cake pans by spraying the bottoms of the pans with non-stick baking spray, lining them with a circle of parchment paper, and then lightly spraying the paper as well.
In the bowl of your stand mixer fitted with the paddle attachment, beat the butter and sugar for 5 minutes on medium speed, scraping the bowl several times, until light and fluffy.
Beat in the eggs, one at a time, beating each for 15 seconds before adding the next.
Scrape the bowl down and beat in the vanilla.
In a separate bowl, sift together the flour, baking powder and salt. In another bowl, combine the buttermilk and sour cream.
With the mixer on low, add the flour mixture in three additions, alternating with the buttermilk/sour cream, starting and ending with the flour. Use a spatula to finish bringing the batter together so that you don't over-mix.
Divide the batter between the pans, smooth out the top of the batter and tap the pans a few times on the counter to release any bubbles.
Bake the cakes on the center oven rack for about 30 minutes, until a cake tester comes out clean.
Set the pans on a wire cooling rack, cover loosely with a clean kitchen towel, and cool completely in the pans before removing and frosting. It's normal for the cake to settle and shrink a bit as soon as you take it out of the oven.
Buttercream
In the bowl of your stand mixer fitted with the paddle attachment, beat the butter for 1 minute until smooth.
In a separate bowl, whisk together the powdered sugar, cocoa powder, meringue powder and salt. With the mixer running on low, add the dry ingredients by spoonfuls, mixing until combined but clumpy. Add the vanilla.
Turn the mixer up to medium and whip for 5 minutes, scraping the bowl occasionally, until very light and fluffy. Add the milk only if needed for desired spreading/piping consistency. Turn the mixer back to low and mix for 1 minute to reduce any large pockets of air.
Assembly
The cakes are sticky, so it will help to place a small piece of wax paper on top the cake before you turn it out of the pan, so that it doesn't stick and pull apart from your fingers. Remember to remove all the parchment and wax paper from the cake layers as you assemble the cake.
Stack and fill the cakes with the chocolate buttercream, then frost all over with a thin crumb coat of buttercream. Chill the crumb-coated cake in the refrigerator for 20 minutes.
Finish frosting the cake with a final swirly layer of buttercream.
Notes
FREEZINGThe cake layers can be baked in advance, wrapped individually in plastic wrap, and frozen until needed. Thaw out overnight before frosting.The assembled and frosted cake can also be frozen, in a bakery box or cake carrier, for several weeks. Thaw out overnight in the refrigerator, then set out to come to room temperature before serving.LEFTOVERSThe leftover cake will stay soft, moist and fresh for days, if kept in an airtight container or cake carrier. No need to refrigerate leftover cake.Any extra buttercream can be frozen in a zip bag for another use.STICKY CAKESThe cakes are very moist and sticky. I STRONGLY recommend that you do not skip the steps of using parchment paper in the bottom of your cake pans, and placing a piece of wax paper on top of the cake to turn it out of the pan. If you don't, you risk the cake sticking to the pan and your hand, causing it to fall apart.
Keyword Butter Cake, Chocolate Buttercream, High Altitude, Yellow Cake