Chelsea's birthday cake

I made this cake for my sister for her birthday. Sadly, I need to take some cake decorating classes! I haven't actually tasted the cake, but Chelsea said it is delicious and everyone wants the recipe!

Rich Chocolate Cake

2 cups flour
1 cup cocoa
2 tsp. baking powder
1 tsp baking soda
1/2 tsp salt
1 cup butter
2 cups sugar
4 large eggs
2 tsp vanilla
1 1/3 cups milk

Preheat oven to 350 degrees. Combine flour, cocoa, baking powder, baking soda, and salt. Set aside. With a mixer at low speed, beat butter and sugar until light and fluffy (about 5 minutes). Add eggs, one at a time, beating after each addition. Beat in vanilla. Then, add flour mixture alternately with milk. Beat until batter is smooth. Pour batter into prepared pan(s). Either one 9x13 or three 8 inch round pans. (I put wax paper in the bottom of my round pans, then grease and flour them). Bake 40-45 minutes for a 9x13 or about 30 minutes for 8 inch rounds. Cool on a wire rack.

Frosting:
Boil 1/2 cup butter with 1/4 cup cocoa. Remove from heat, add 6-8 cups powdered sugar and 1/3 cup milk. Beat until smooth.