Preheat oven to 350°F. Grease all 12 muffin cups well. Make sure all wet ingredients are at room temperature to keep the batter from clumping.
Peel and mash bananas using electric hand mixers until very smooth (like applesauce consistency). Measure out exactly 1 leveled cup (discard any extra).
Add 1 cup mashed banana to a large bowl. Add egg, melted and cooled coconut oil, honey, yogurt, and vanilla. Mix with hand mixers until smooth.
Sprinkle baking soda, baking powder, cinnamon, and salt over the wet mixture. Mix until just combined.
Add flour and optional chocolate chips, nuts, or coconut. Mix until just combined and no dry streaks remain. Don’t over-mix.
Divide batter evenly among the 12 muffin cups (they’ll be nearly full). Sprinkle 1/2 teaspoon oats or coconut flakes on top if you'd like. Bake for 18–23 minutes, or until a toothpick comes out clean or with a few moist crumbs.
Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
Video
Notes
Storage: Store at room temp in an airtight container for 2 days, or in the fridge for up to 1 week. Freeze for up to 3 months. Thaw at room temp or microwave to warm.