Preheat oven to 450°F. Line or grease muffin tray.
In a large bowl, combine flour, baking powder, baking soda, sugar, protein powder, and 1 cup chocolate chips.
In another bowl, whisk melted butter, eggs, milk, and mashed banana.
Fold dry ingredients into wet ingredients until just combined.
Scoop into muffin tray. Top with remaining ¼ cup chocolate chips and decorative sugar.
Bake 5 minutes at 450°F, then reduce oven to 375°F and bake for 15 more minutes.
Cool before enjoying!