Prepare the Oven and Pan

• Preheat the oven to350°F (175°C).
• Grease a 9 × 5-inch loaf pan and line it with parchment paper, leaving some overhang for easy removal.

Make the Cookie Dough

• In a medium bowl, beat the softened butter, brown sugar, and granulated sugar until creamy.
• Mix in the vanilla extract.
• Add the heat-treated flour and stir until combined.
• Add the milk gradually until the mixture becomes soft and dough-like.
• Fold in the mini chocolate chips.
• Refrigerate the cookie dough while preparing the banana bread.

Prepare the Banana Bread Batter

• In a large bowl, mash the ripe bananas until mostly smooth.
• Whisk in the melted butter and sugar.
• Add the eggs, vanilla extract, and sour cream. Mix until well combined.
• In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon.
• Gradually fold the dry ingredients into the wet ingredients until just combined. Avoid overmixing.
• Fold in the mini chocolate chips.

Assemble the Loaf

• Pour half of the banana bread batter into the prepared loaf pan.
• Break the chilled cookie dough into small pieces and scatter some over the batter.
• Add the remaining banana bread batter.
• Scatter the remaining cookie dough pieces over the top and gently press them into the batter.
• Sprinkle with extra mini chocolate chips if desired.

Bake the Banana Bread

• Bake for55–70 minutes, or until a toothpick inserted into a section without a large piece of cookie dough comes out with a few moist crumbs.
• If the top browns too quickly, loosely cover the loaf with foil during the final 15–20 minutes.
• Allow the bread to cool in the pan for 15–20 minutes before transferring it to a wire rack.

Cool and Serve

• Let the banana bread cool completely before slicing so the cookie dough swirl can set.
• Serve at room temperature or warm individual slices slightly for a softer, chocolate-filled treat.