Prep your pan and oven: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease lightly.
Mash the bananas: In a large mixing bowl, mash the ripe bananas until mostly smooth with a few small lumps.
Whisk in wet ingredients: Add the eggs, Greek yogurt, maple syrup, melted coconut oil, and vanilla.
Whisk until well combined.
Mix dry ingredients: In a separate bowl, whisk together the flour, cocoa powder, protein powder, baking soda, baking powder, and salt.
Combine wet and dry: Add the dry ingredients to the wet. Stir gently with a spatula until just combined. If the batter is very thick, stir in milk 1 tablespoon at a time.
You’re aiming for a thick but scoopable batter.
Fold in chocolate chips: Gently fold in the chocolate chips, reserving a few for topping if you like.
Fill the muffin cups: Divide the batter evenly among the 12 cups. Top with extra chips for a bakery-style look.
Bake: Bake for 16–20 minutes, or until a toothpick comes out with a few moist crumbs. The tops should spring back lightly when touched.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a rack to cool completely.
This helps them set and stay tender.