1 1/2 c. butter
2 c. sugar
1 c. light brown sugar
6 eggs (large)
2 c. plain flour
1/2 c. cocoa
1 tsp. vanilla
8 oz. sour cream
1/4 tsp. baking soda

Beat butter at medium speed with electric mixer for 2 minutes. Gradually add sugars, beating about 6 minutes. Add eggs, one at a time, beating until yellow disappears. Combine flour, cocoa and soda. Add to butter mixture with sour cream alternately. Beat at low speed until blended; stir in vanilla. Pour into a greased and floured Bundt pan.

Bake at 325°F for 1 hour and 40 minutes. Cool for 10 to 15 minutes in pan. Remove from pan and cool on wire rack.