Preheat and prep: Heat your oven to 350°F (175°C). Lightly grease a mini muffin tin or line with mini paper liners to prevent sticking.
Mix dry ingredients: In a large bowl, whisk together the protein powder, cocoa powder, almond flour, baking powder, salt, and espresso powder if using. Break up any lumps for a smooth batter.
Whisk wet ingredients: In a separate bowl, mix the mashed banana, Greek yogurt, egg, vanilla, maple syrup, and oil until smooth and creamy.
Combine: Pour the wet mixture into the dry ingredients.
Stir gently with a spatula until just combined. The batter will be thick but scoopable—avoid overmixing.
Add chocolate: Fold in the dark chocolate chips. Save a few to sprinkle on top for that bakery-style look.
Fill the tin: Scoop the batter into the mini muffin cups, filling each about 3/4 full.
Top with the reserved chips.
Bake: Bake for 10–12 minutes, or until the tops are set and a toothpick comes out with a few moist crumbs. Do not overbake—this keeps them fudgy.
Cool: Let the bites cool in the pan for 5 minutes, then transfer to a rack to cool completely. They firm up as they cool.
Serve: Enjoy warm for melty centers, or chill for a chewier, truffle-like texture.