Preheat oven to 350°F.
Line an 8x8 pan with parchment paper. Set aside.
In a small bowl, whisk together melted butter and white sugar.
1/2 cup butter, 1 cup white sugar
Add in mashed bananas and continue whisking.
1/2 cup mashed bananas
Add in egg and vanilla and continue whisking.
1 egg, 1 tbsp vanilla
Toss in the cocoa powder, flour, and salt. Switch over to a whisk and gently fold until a soft batter forms. Don't overmix!
1/2 cup + 2 tbsp all-purpose flour, 1/2 cup dark cocoa powder, 1/4 tsp salt
Mix in chocolate chips.
1/2 cup semi-sweet chocolate chips
Transfer into prepared pan and spread out evenly.
Bake for about 35 minutes or until an inserted toothpick comes out with a few damp crumbs. Allow to cool before slicing.