Prep your pan and oven: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease with oil spray.
Mash the bananas: In a large bowl, mash the bananas until mostly smooth.
A few small lumps are fine.
Whisk in wet ingredients: Add eggs, Greek yogurt, maple syrup, vanilla, and melted oil. Whisk until creamy and well combined.
Mix dry ingredients: In a separate bowl, stir together flour, oats, protein powder, baking powder, baking soda, cinnamon, and salt.
Combine gently: Add the dry mix to the wet bowl. Stir with a spatula until just combined.
Do not overmix; a few streaks are okay.
Fold in extras: If using nuts, chocolate chips, or berries, fold them in now.
Portion the batter: Divide evenly among the muffin cups. They should be about 3/4 full.
Bake: Bake 16–20 minutes, or until the tops spring back lightly and a toothpick comes out with a few moist crumbs.
Cool: Let muffins rest in the pan for 5 minutes, then move to a wire rack to cool completely. This helps set the structure.
Serve or store: Enjoy warm or at room temperature.
Add a smear of peanut butter for extra protein and healthy fats.