Preheat your oven to 350 degrees Fahrenheit. Spray a 9 by 5 inch loaf pan well with cooking spray.
In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt.
1 2/3 cups all-purpose flour, 1/3 cup unsweetened cocoa powder, 3/4 teaspoon baking soda, 1/2 teaspoon salt
In a medium bowl, whisk together the bananas, cooled butter, eggs, sour cream, sugar, and vanilla.
3/4 cup sugar, 6 tablespoons unsalted butter melted and cooled, 2 large eggs at room temperature and lightly whisked, 1/4 cup sour cream, 1 teaspoon vanilla extract
Gently fold the wet ingredients into the dry ingredients. Be careful not to overmix. Stir in the chocolate chips.
1 cup milk chocolate chips
Pour the bread batter into the prepared pan. Bake for 60 to 70 minutes or until a toothpick inserted slightly off-center in the bread comes out with just a few crumbs. Allow the bread to cool in the pan for 10 minutes. Then remove and allow to cool on a cooling rack for 35 minutes before slicing and enjoying.