Preheat the oven to 350℉/176℃. Line two baking trays with parchment paper and set aside. Melt the butter and allow it to cool as the rest of the ingredients are being measured.
1/2 cup unsalted butter
In a bowl, add the flour, oats, cocoa (sifted), baking soda, baking powder, cinnamon, cornstarch, and salt. Stir to combine and set aside.
1 1/2 cups all-purpose flour, 1 3/4 cups rolled oats, 1/3 cup unsweetened cocoa powder, 1 tsp baking soda, 1 3/4 tsp baking powder, 1/4 tsp salt, 1/4 tsp cinnamon, 1 tsp cornstarch
In a large bowl, add the melted and slightly cooled butter, brown sugar, and white sugar. Whisk together for 2-3 minutes vigorously until combined.
1/2 cup dark brown sugar, 1/3 cup white sugar
Add in the mashed bananas, eggs, and vanilla. Continue to whisk for another minute or two. The mixture may appear chunky from the bananas, that is normal.
2 large eggs, 1 tbsp vanilla, 1/2 cup mashed bananas
Add in the dry ingredients. With a spatula, gently fold just until a soft cookie dough forms. Do not over-mix!
Add in the chocolate chips and mix in just until combined and evenly distributed.
3/4 cups semi-sweet chocolate chips
Scoop 6 cookies per tray, spacing them out evenly from one another. Bake for 14-16 minutes. Add extra chocolate chips on top. The cookies are ready when the edges are dry and completely baked, and the middles still look slightly puffy and underbaked. Remove from the oven, allow to cool on pan, and enjoy!