Make the brown butter. Cut the butter in small pieces and heat the butter in a small pan on medium heat for about 3-5 minutes until the butter turns an amber color. The butter will first foam and start to pop. Then, brown bits will begin to form in the bottom of the pan. Once browned and popping slows, it is ready. You should smell a nutty aroma. Scrap the butter (and all the of those magical brown bits into a heat-safe bowl and let rest for about 15 minutes.

In a medium mixing bowl, sift the flour, baking soda, baking powder, and salt. Set aside.

In a large mixing bowl, add the granulated sugar, brown sugar, cooled browned butter, vanilla, and cinnamon, and beat with a hand mixer for 2-3 minutes. Then, add the mashed banana and beat until well combined. Next, add the egg and beat until well combined.

Add your "sifted flour mixture" into your wet batter and mix with a wooden spoon or rubber spatula until combined. Be sure not to over mix.

Fold in your chocolate and nuts.

Optional: transfer the cookie dough to a fridge and let chill for at least 45-60 minutes to allow the flour to hydrate and obtain those brown butter, banana, vanilla, and cinnamon flavors

Preheat your oven to 350°F. Line a 9X9 baking dish (or 8x8 if you are looking for thicker bars) with parchment paper and lightly grease. Set aside.

Next, remove your chilled dough from the refrigerator and transfer to the prepared baking dish. Add additional chocolate chips and walnuts if desired.

Let bars bake in the oven for about 18-25 minutes or until edges are set . Once done, take the bars out and immediately top with flaky sea salt. Let cool for at least 30 minutes or until set.