- 2 cups all-purpose flour
- 1 3/ 4 cups granulated sugar
- 3/ 4 cup unsweetened, dark, Dutch-processed cocoa powder
- 1/ 2 teaspoon baking powder
- 1 1/ 4 teaspoons baking soda
- 1 teaspoon coarse Kosher salt
- 4 large eggs
- 1 cup whole milk
- 1 cup full-fat sour cream
- 1 cup vegetable oil
- 2 teaspoons vanilla extract
- 1 1/ 2 cups unsalted butter, softened to room temperature
- 3 cups powdered sugar
- 1 tablespoon meringue powder (optional)
- 1 1/ 2 teaspoons vanilla extract
- 1/ 4 cup full-fat sour cream
Preheat the oven to 350. Spray the bottoms of three 8-inch round cake pans with non-stick spray.
In a bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda and salt, then whisk until completely combined.
In another large bowl, whisk together the eggs, milk, sour cream, oil and vanilla until smooth. Add the dry ingredients to the wet, and whisk for about 30 seconds until well combined and mostly free of lumps.
Divide the batter between the pans. Tap the pans lightly on the counter a few times to pop any large air bubbles. Bake the cakes on the center rack for about 25-30 minutes, until a toothpick or cake tester comes out clean or with moist crumbs clinging to it, and the tops spring back when gently touched.
Set the pans on a wire rack, cover loosely with a clean kitchen towel and cool completely before frosting.
In the bowl of your stand mixer fitted with the whisk attachment, beat the butter for one minute until smooth. With the mixer on low, add the powdered sugar and meringue powder, mixing to combine. Add the vanilla and the sour cream; whip on medium speed for 4-5 minutes, scraping the bowl occasionally, until very light and fluffy. If the buttercream is too stiff, you can add a little more sour cream or milk, one tablespoon at a time, until you reach the desired consistency.
Stack and fill the cooled cakes with the buttercream, then frost all over with a thin crumb coat of buttercream. Chill in the refrigerator for 30 minutes, then finish frosting the cake with a final layer of buttercream.