Preheat the oven to 350°F (175°C). Line or lightly grease a muffin pan.
Add the mashed banana, eggs, maple syrup, almond butter, almond milk, vanilla, protein powder, baking powder, and salt to a blender.
Blend until smooth, scraping down the sides as needed.
Stir in the chocolate chips or pulse very briefly.
Divide the batter between the muffin cups, filling each about 3/4 full.
Add a few extra chocolate chips on top if desired.
Bake for 18–22 minutes, until the tops are set and a toothpick comes out mostly clean with a few moist crumbs.
Cool in the pan for 5–10 minutes, then transfer to a wire rack.