Preheat oven to 350°. Spray a 9x5-inch loaf pan with baking spray with flour. (I used four mini loaf pans - 5 ¾ x 3 ¼ x 2 ¼. Don’t fill more than ⅔ full.)

Prepare Streusel Topping: In a small bowl, whisk together sugar and flour. Add butter and mix until mixture has a sandy texture. Set aside.

In a medium bowl, mix together flour, baking powder, baking soda, and salt; set aside.

In a large bowl, mix the mashed bananas, sugar, sour cream, eggs, melted butter, and vanilla until well blended. Add flour mixture to banana mixture, mix just until moistened. Stir in chocolate chips.

Spoon batter into prepared pan. Top with streusel topping.

Bake for 45 to 55 minutes (bake mini loaves for 30 minutes), or until a wooden pick inserted in center comes out clean.

Cool 10 minutes in pan on a wire rack; remove from pan, and cool completely on a wire rack before cutting.