1 c. sugar
3/4 c. butter
2 1/2 c. flour
1 c. sour cream
2 eggs
1 tsp. baking powder
1 tsp. baking soda
1 tsp. vanilla
1 c. chocolate chips
1/2 c. packed brown sugar
1 1/2 tsp. cocoa
1/2 c. chopped walnuts

Grease a 9 inch tube pan. In a large bowl, with mixer at medium speed, beat sugar with 1/2 cup butter until light and fluffy. Add 2 cups flour and next 5 ingredients; beat at low speed until blended, constantly scraping the bowl with a rubber spatula. Increase speed to medium, beat 3 minutes, occasionally scraping bowl. With a spoon mix in 1/2 cup chocolate chips. Spread batter evenly in pan. In another bowl, mix 1/2 cup flour, brown sugar, and cocoa. Cut in 1/4 cup butter until mixture resembles coarse crumbs. Stir in nuts and rest of chocolate chips. Crumble evenly over batter in pan. Bake 45-55 minutes at 350 degrees.