Preheat oven to 350° F (175° C).
Line an 8x8" pan with parchment paper and set aside.*
In a large mixing bowl add banana, eggs and vanilla. Blend using an electric mixer or wire whisk. Add melted coconut oil and coconut sugar and beat again to combine.
Add almond flour, coconut flour, cocoa powder, baking powder, baking soda and salt and either beat until just blended in with a hand mixer or stir in by hand.
Stir in chocolate chips* and spread batter into parchment lined baking pan until evenly distributed (batter will be very thick).
Bake in preheated oven for 20-25 minutes until a toothpick inserted into the center of the pan comes out without wet batter on it (toothpick may be tinged brown and might have crumbs or melted chocolate on it but shouldn't have batter stuck to it).
Allow to cool in the pan for 20-30 minutes until brownies are cool. While brownies are cooling, place 3 tablespoons chocolate chips and 1 teaspoon coconut oil into a microwave safe container for 30 seconds. Stir and microwave for additional 10 second intervals if needed until chocolate is melted. Alternatively, chocolate can be melted in a small pan on the stovetop on low heat.
Use a spoon to drizzle melted chocolate over brownies in a zig zag pattern. Once chocolate has dried, cut into 9 brownies and serve. Store in an airtight container on the counter for up to 3 days.