Makes: 12 servings at 28o each.Prep: 25 minutes.Bake: at 350 degrees for 60 minutes.
1. Heat oven to 350 degrees F. Grease and flour 10-inch tube pan.
2. Sift flour, baking soda, baking powder and salt onto waxed paper.
3. Beat butter and sugar in a medium-size bowl on medium speed until light and fluffy, about 3 minutes. Beat in the eggs, one at a time, beating well after each addition.
4. On low speed, beat flour mixture into butter mixture in 3 additions, alternating with sour cream, in 2 additions; beat on medium speed for 3 minutes.
5. Fold in chocolate pieces. With rubber spatula, scrape batter into prepared tube pan; smooth top.Crumb Topping:
6. Whisk brown sugar, flour, cinnamon and salt in small bowl. Using pastry blender or 2 knives held like scissors, cut in cold butter until mixture is consistency of coarse cornmeal. Sprinkle the crumb mixture evenly over the batter in the tube pan.
7. Bake in 350 degree F oven 60 minutes or until wooden pick inserted in center comes out with moist crumbs attached. Cool cake in pan on rack 20 minutes. Gently turn out cake. Let cool on rack, crumb side up.