classic chocolate layer cake

Instructions

1. Preheat oven to 350°F and spray three 9-inch round cake pans with nonstick spray. Whisk together flour, cocoa, baking powder, baking soda, and salt in a large bowl; make a well in the center of the mixture. Add sugars, eggs, egg yolk, milk, yogurt, oil, and vanilla to flour mixture; whisk in just until incorporated. Dissolve instant espresso in boiling water; add to batter and whisk in just until smooth.
2. Divide batter evenly between cake pans and smooth with an offset spatula. Tap pans sharply to reduce air bubbles. Bake for 17 to 19 minutes, until a toothpick inserted in the center comes out clean or with a few crumbs, and the edges are pulling slightly away from the pan. Cool cakes completely in pans on a wire rack.
3. For the frosting, combine melted butter, vanilla, salt, powdered sugar, cocoa, and milk in a large bowl and whisk until well combined. Whisk frosting one more minute, until smooth and glossy, then use immediately.
4. To assemble, place one cake layer on a rotating cake stand. Use an offset spatula to spread about 1/2 cup frosting over the layer. Add second cake layer and spread about 1/2 cup frosting over the layer.
5. Repeat the process of frosting to the top cake layer, swirling the frosting generously over the edge of the layer. Use the offset spatula to apply frosting to the sides of the cake while you rotate the cake stand, then use a bench scraper to gently smooth the edges of the cake and remove any excess frosting. Top with sprinkles.