2 1/4 C cake flour (sifted, then measured)
2T unsweetened cocoa powder
1 tsp baking powder
1 tsp baking soda
1/2 tsp salt
1 C buttermilk (1 T vinegar to 1 C milk. use WHOLE milk)
1 T red food coloring
1 tsp distilled white vinegar
1 tsp vanilla extract
1 1/2 C sugar
1/2 C (1 stick) unsalted butter, room temperature
2 large eggs
Preheat oven to 350 degrees. Butter and flour 2 9" diameter cake pans with 1 1/2" sides. Sift sifted flour, cocoa powder, baking powder, baking soda, and salt into medium bowl. Whisk buttermilk, food coloring, vinegar, and vanilla in small bowl to blend. Add eggs 1 at a time, beating after each addition. Beat in dry ingredients in 4 additions alternately with buttermilk mixture in 3 additions.
Divide batter between pans. Bake cakes until tester inserted into center comes out clean, about 27 minutes. Cool in pans on racks 10 minutes. Turn cakes out onto racks; cool completely.
Frosting:
2 8oz packages cream cheese, room temperature
1/2 C unsalted butter, room temperature
1 T vanilla extract
2 1/2 C powdered sugar
Beat cream cheese and butter in large bowl until smooth. Beat in vanilla. Add powdered sugar and beat until smooth. Place one cake layer, flat side up, on platter. Spread one cup of frosting over top of cake. Top with second layer, flat side down. Spread remaining frosting over top and sides of cake.
Cake can be made one day ahead. Cover and refrigerate. Let stand at room temperature one hour before serving.