1 c. butter, softened
2 c. sugar
1 c. firmly packed brown sugar
6 lg. eggs
2 1/2 c. all-purpose flour
1/4 tsp. baking soda
1/2 c. cocoa
1 (8 oz.) carton sour cream
2 tsp. vanilla extract
Powdered sugar (optional)

Beat butter at medium speed with an electric mixer about 2 minutes or until soft and creamy. Gradually add sugars, beating at medium speed 5-7 minutes. Add eggs, one at a time, beating just until yellow disappears.

Combine flour, baking soda and cocoa; add to creamed mixture alternately with sour cream, beginning and ending with flour mixture. Mix at lowest speed just until blended after each addition. Stir in vanilla.

Spoon batter into a greased and floured 10 inch tube pan. Bake at 325 degrees for 1 hour and 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10-15 minutes; remove from pan and cool completely on a wire rack. Sprinkle with powdered sugar, if desired.