Preheat the oven to 350°F. Line a 9-inch square pan with parchment paper and grease the paper with either cooking spray or butter.
Mix all the dry ingredients - all-purpose flour, cocoa powder, sugar, baking soda, and salt till they are combined. Set aside.
In a mixing bowl, add the mashed bananas, coconut oil, vanilla extract, and eggs and mix them well. Add the flour mixture and 1/4th cup chocolate chips and mix them till they are combined.
Pour the batter into the greased pan and sprinkle on chocolate chips over it. Bake for 25 minutes until a toothpick inserted in the center comes out clean. ( I checked at the 23-minute mark and it was done)
Remove from the oven and let the cake cool in the pan for a few minutes before transferring it to a wire rack to cool completely.
Use a serrated knife to cut the cake into slices.