Preheat oven to 350°F (175°C). Use a silicone muffin pan or line a mini muffin tin with paper liners or grease with butter.
n a large bowl, mash bananas until smooth. Stir in Greek yogurt, honey (or maple syrup), egg, and vanilla extract.
In a separate bowl, whisk flour, baking powder, baking soda, salt, and cinnamon (if using).
Gently fold the dry ingredients into the wet mixture until just combined. Avoid overmixing.
Stir in melted butter, then fold in chocolate chips or nuts if using.
Fill muffin tin about ¾ full.
Bake for 10-12 minutes, or until a toothpick inserted into the center comes out clean.
Cool muffins in the tin for a few minutes, then transfer to a wire rack.