1. Cream together the butter and sugar.
2. Add eggs one-at-a-time.
3. Gradually add the flour, baking powder, baking soda and salt.
4. When dry ingredients are completely blended, add the sour cream& vanilla.
5. Fold in the chocolate bits.
6. Prepare streusal by mixing all ingredients together.
7. Pour 1/2 of the batter into prepared loaf or tube pan.
8. Top with 1/2 of the streusal.
9. Add remaining batter on top of streusal.
10. Top with with remaining streusal.
11. Bake for one (1) hour at 350 degrees.