Preheat oven to 350 degrees. Generously grease a 9-by-5-inch loaf pan with nonstick cooking spray and set aside.

In a medium bowl, whisk together the flour, cocoa powder, baking soda, baking powder and salt.

In a large bowl, combine the bananas and oil and stir until combined. Add  the brown sugar, egg, sour cream and vanilla and stir until smooth.

Add the dry ingredients to the wet ingredients, and stir gently until just combined. Don’t overmix. Stir in 3/4 cup of the chocolate chips.

Pour batter into prepared pan. Sprinkle the remaining 1/4 cup of chocolate chips over the top of the bread. Bake for 50-65 minutes, or until a toothpick inserted into the center of the bread comes out clean. (You may still have some chocolate on your toothpick from the chocolate chips).

Remove the pan from the oven and set on a wire cooling rack. Allow bread cool in the pan for 10-15 minutes before turning onto the wire rack to cool completely.