01 -
Preheat oven to 350°F. Grease a 9x5 inch loaf pan with cooking spray and set aside.
02 -
In a medium bowl, whisk together flour, cocoa powder, baking soda, and salt until fully incorporated and no lumps remain.
03 -
In a large bowl, beat butter, granulated sugar, and light brown sugar on high speed with a hand mixer for 2 minutes until creamy.
04 -
Add eggs, mashed bananas, sour cream, and vanilla extract to the butter mixture. Beat for 1 to 2 minutes until smooth and uniform, scraping sides of bowl as needed.
05 -
Add dry ingredients to wet ingredients and mix on low speed until just combined and no flour streaks remain. Scrape bowl sides with a spatula as necessary.
06 -
Gently fold milk chocolate chips into the batter using a rubber spatula until evenly distributed.
07 -
Pour batter into prepared pan and spread evenly. Bake for 55 to 60 minutes, testing doneness with a toothpick inserted in the center; if it comes out clean, it is done. If not, bake an additional 5 to 10 minutes.
08 -
Remove from oven and cool in pan for 15 minutes. Run a knife around the edges to loosen, then transfer to a wire rack to cool completely.
09 -
While bread cools, combine 1/3 cup milk chocolate chips and 2 tablespoons whole milk in a small bowl. Microwave for 15 seconds, then stir until melted. Whisk in powdered sugar until smooth, and allow to rest until bread is fully cooled.
10 -
Drizzle the cooled chocolate topping over the banana bread. Slice and serve.