1 1/2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon baking powder
1/2 cup unsalted butter, softened
1 cup white sugar
1 teaspoon vanilla extract
1 cup sour cream
6 ounces semisweet chocolate chips
1/2 cup finely chopped walnuts
1/4 cup white sugar
1 teaspoon ground cinnamon
Preheat oven to 350 degrees F (175 degrees C). Grease and flour one 8x8 inch or 4 mini loaf pans. In a medium bowl, mix flour, soda, baking powder and baking soda. Set aside. In a large bowl, cream butter and sugar until light and fluffy. Add eggs one at a time, mixing well each time. Add vanilla. Add flour mixture alternately with sour cream. Mix until well blended. Stir in chocolate chips.
Make streusel mixture: In a medium bowl, mix walnuts, sugar and cinnamon together until blended.
Pour in half the batter and sprinkle some streusel mixture across the pan (s). Add remaining batter and sprinkle streusel mixture on the top. Bake at 350 degrees F (175 degrees C). Bake 30 minutes for mini loaves and 45 minutes for 8x8 inch pan.