Prepare the Cookie Dough:
In a mixing bowl, beat the softened butter with the granulated sugar and brown sugar until light and fluffy, about 2-3 minutes.
Add vanilla extract and milk, mixing until incorporated.
Gradually add the flour and salt, stirring until combined.
Fold in the mini chocolate chips. Set the cookie dough aside to firm up in the fridge while you prepare the banana bread batter.
Make the Banana Bread Batter:
Preheat your oven to 350°F (175°C). Grease and flour a loaf pan (8x4 or 9x5).
In a large mixing bowl, mash the ripe bananas. Add the melted butter and mix well.
Stir in the sugar, eggs, and vanilla extract until fully combined.
In a separate bowl, whisk together the flour, baking soda, salt, and cinnamon (if using). Gradually add the dry ingredients to the banana mixture, alternating with the milk. Mix until just combined.
Assemble the Bread:
Scoop spoonfuls of the cookie dough and gently fold them into the banana bread batter, leaving some small chunks of cookie dough visible. Be careful not to over-mix.
Pour the batter into the prepared loaf pan and smooth the top.
Bake the Banana Bread:
Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean (with a few crumbs). If the top starts to brown too quickly, tent with foil.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.