Easy Chocolate Cake Recipe

While the cakes bake, clean the mixing bowl and make the buttercream: Add the butter to the bowl and mix on medium-high until smooth, stopping the mixer occasionally to scrape the bottom and sides of the bowl. Add the confectioners’ sugar, cocoa powder, sour cream, milk, vanilla extract and salt. Mix on low until the sugar and cocoa are moistened, then turn the speed up to medium-high and whip until smooth and fluffy, about 5 minutes, adding a bit more milk (1 teaspoon at a time) if necessary to make a smooth and light buttercream. Scrape the bowl occasionally to ensure that the buttercream is evenly mixed. Taste and add a bit more salt if desired. (The buttercream can be kept at room temperature while the cake finishes baking and cooling.)