Preheat your oven to 350°F (175°C).
Line a muffin tin with parchment paper liners or grease with cooking spray.
Mash the ripe bananas in a medium bowl until smooth.
In a large bowl, whisk together the melted butter, brown sugar, and granulated sugar until well combined. Add the mashed bananas, Greek yogurt, egg, and vanilla extract.
In another bowl, whisk together the flour, baking powder, baking soda, salt, and ground cinnamon.
Gently fold the dry ingredients into the wet ingredients with a rubber spatula.
Evenly distribute the batter among the prepared muffin cups, filling each about 2/3 full.
Bake for 18-20 minutes, or until a toothpick comes out clean.
Allow the muffins to cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely.