Step 1

Preheat the oven to 350°F (180°C). Grease a 9 x 5-inch loaf pan with nonstick cooking spray. Line the pan with parchment paper, leaving some overhang on the long sides so it will be easy to lift out the bread, and spray again.

Step 2

Add the butter to a medium nonstick pan over medium heat. Cook, stirring occasionally, until the butter turns amber brown and smells nutty, about 3–4 minutes. Watch carefully so the butter does not burn. Remove the pan from the heat and set aside to cool for 10–15 minutes.

Step 3

Add cooled brown butter and brown sugar to a large bowl. Beat with an electric hand mixer on medium speed until evenly combined, about 1 minute. Add the egg and beat until light and fluffy, 3–4 minutes.

Step 4

In a medium bowl, combine the mashed bananas, sour cream, and vanilla and mix with a rubber spatula until well combined.

Step 5

In a separate medium bowl, whisk together the flour, salt, baking soda, and cinnamon.

Step 6

Alternate adding the flour mixture and banana mixture to the butter mixture, starting and ending with flour and folding with a rubber spatula between each addition until just incorporated. Fold in the chocolate chunks.

Step 7

Pour the batter into the prepared loaf pan and smooth with an offset spatula, then sprinkle the turbinado sugar on top.

Step 8

Bake the banana bread until golden brown and a toothpick or cake tester inserted in the center comes out clean, 60–70 minutes. Set the loaf pan on a wire rack to cool for at least 1 hour, then lift out the banana bread and slice.

Step 9

Enjoy!