Prep the pan and oven: Preheat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease with oil.
Make oat flour if needed: Add 2 cups rolled oats to a blender and blend until fine and flour-like. Don’t overblend; stop when it looks like a coarse flour.
Mash the bananas: In a large bowl, mash the bananas with a fork until mostly smooth with a few small lumps.
Whisk the wet ingredients: Add eggs, maple syrup or honey, Greek yogurt, melted oil, and vanilla. Whisk until well combined.
Stir in the dry ingredients: Add oat flour, whole rolled oats (if using), baking soda, baking powder, cinnamon, and salt. Stir gently with a spatula until just combined. The batter will be thick.
Fold in extras: If using chocolate chips, nuts, or berries, fold them in now. Don’t overmix.
Fill the muffin cups: Divide the batter evenly among the 12 cups, filling each about 3/4 full. For a bakery look, sprinkle a few oats or chocolate chips on top.
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 set and prevents sogginess.
Enjoy: Serve warm or at room temperature. They’re great plain or with a smear of nut butter.