Step 1

Preheat the oven to 350° F. Grease a 9 x 5 x 3-inch loaf pan with non-stick cooking spray.

Step 2

In a medium bowl, combine the flour, cocoa powder, baking soda and salt. Whisk until there are no more lumps in the cocoa powder and the mixture is well combined. Set aside.

Step 3

In a large bowl or electric mixer fitted with the paddle attachment or beaters, beat the butter and sugar until light and fluffy, 2 to 3 minutes. Add the eggs one at a time, incorporating well after each addition. Add the dry ingredients and beat gently until just combined. Add the bananas, sour cream and vanilla and mix on low speed to combine. Fold in the chocolate chips. Do not overmix.

Step 4

Pour the batter into the prepared loaf pan and spread evenly with a spatula. Bake until a toothpick inserted into the center comes out with a few moist crumbs attached, about 1 hour and 10 minutes. Let the loaf rest in the pan for about 10 minutes, run a blunt knife around the edges to loosen, then turn it out onto a rack to cool completely.

Step 5

Note: There are two types of unsweetened cocoa powder: natural (such as Hershey's) and Dutch-processed. Dutch-processed will not work in this recipe.

Step 6

Freezer-Friendly Instructions: The bread can be frozen for up to 3 months. After it is completely cooled, wrap it securely in aluminum foil, freezer wrap or place in a freezer bag. Thaw overnight in the refrigerator before serving.