Preheat your oven to 375 degrees, and line a mini muffin pan with liners. Set aside.
In a medium bowl, stir together the flour, almond flour, cocoa powder, baking powder, baking soda, and salt. Reserve about 1 tablespoon of this flour mixture. Set aside.
In a large bowl, beat together the bitter and sugar until fluffy. Add in the eggs, vanilla extract, and mashed banana, and beat until combined.
Add the flour mixture and the buttermilk into the butter mixture in parts, alternating, starting and ending with the flour mixture. Beat until completely combined. Toss the chocolate chips with the reserved flour mixture, and fold into the batter.
Scoop the batter into your prepared muffin tins. If you don't have multiple pans, you'll be baking in a few batches here. Bake for 10-12 minutes, or until a cake tester comes out clean. Cool and enjoy!