Prep your pan: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with liners or grease lightly.
Mash the bananas: In a large bowl, mash bananas with a fork until mostly smooth with a few small lumps.
Whisk the wet ingredients: Add eggs, maple syrup (or honey), Greek yogurt, oil, and vanilla.
Whisk until combined.
Add the dry ingredients: Stir in oats, flour, baking powder, baking soda, cinnamon, and salt. Mix just until no dry streaks remain.
Fold in extras: If using nuts, chocolate chips, or fruit, gently fold them into the batter.
Fill the cups: Divide the batter evenly among the 12 muffin cups. They should be nearly full.
Bake: Bake for 18–22 minutes, or until the tops are set and a toothpick comes out clean or with a few moist crumbs.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
This helps them stay fluffy.