Preheat oven to 350°F (175°C). Grease 4 small ramekins or lightly spray with non-stick cooking spray.
Mash the bananas in a large bowl until smooth.
Add wet ingredients: Mix in eggs, milk, vanilla, and maple syrup (if using).
Combine dry ingredients: Stir in oats, baking powder, cinnamon, salt, and protein powder (if using) until well combined.
Fold in mix-ins: Add chocolate chips or nuts, leaving a few to sprinkle on top if you like.
Divide the batter evenly among the 4 ramekins. Smooth the tops slightly.
Bake for 25–30 minutes, or until the tops are golden and a toothpick inserted into the center comes out clean.
Cool slightly before serving. Enjoy warm, or let cool and cover for meal prep—these keep well in the fridge for up to 4 days.