Preheat the oven to 350℉. Line two baking trays with parchment paper and set aside. Mash the bananas and set aside.
1/2 cup mashed bananas
Brown the butter: In a medium sized saucepan, add the butter and melt it on medium heat. Once it melts, it will crackle, then become foamy – continue mixing the butter while this happens to prevent burning. The butter will go from melted to golden brown quickly, and you'll know it's almost done when the aroma of browned butter arrives. The whole process should take about 5 minutes! Once golden, remove from heat and transfer to a glass bowl to cool for 20 minutes while you prep the rest of the ingredients.
1/2 cup + 1 tbsp unsalted butter
In a medium bowl, add in flour, cinnamon, baking soda, baking powder, cornstarch, and salt.
1 tsp baking soda, 1/2 tsp cinnamon, 1 tbsp cornstarch, 2 cups all-purpose flour, 1/4 tsp salt
In a large bowl, add in slightly cooled brown butter, brown sugar, and white sugar. Whisk until well combined, about 2 minutes. Then add in the egg, vanilla, and mashed bananas. Continue whisking until all combined.
1/2 cup + 1 tbsp unsalted butter, 1/2 cup dark brown sugar, 1/4 white sugar, 1 large egg, 1 tbsp vanilla
Add the dry into the wet. Using a spatula, mix until a soft cookie dough forms. Don't over-mix! *If your batter is runny, allow it to sit on your counter for 5-10 minutes and allow the flour to hydrate and thicken the cookie dough before scooping*.
Toss in the chocolate chips and mix a few more times.
3/4 cups semi-sweet chocolate chips
Scoop the cookies (I used a 2 tbsp cookie scooper) onto the prepared baking tray placing them about 2 inches apart from one another. Bake 6 at a time for 14-16 minutes or until the edges are a light golden brown. If the cookies are not spreading, gently bang them on the ground or countertop and place back into the oven to bake. After about 14-16 minutes, the cookies should be ready. The middle may look soft and underbaked, but it will continue to bake as it sits on the hot tray.
Store in an airtight container for up to 3 days or in the fridge for a week. You can also freeze the cookies and thaw in the microwave when wanted.