Preheat oven to 375ºF. Line muffin tin with muffin papers or spray with cooking spray.
In a medium bowl, mix together the flour, baking soda, baking powder, salt, and cinnamon. Set aside.
In a large bowl, whisk the egg and sugar together. Add the melted 5 tablespoon butter, vanilla, and mashed bananas. Stir until smooth.
Add the dry ingredients to the wet ingredients and stir until just combined — do not overmix. Spoon the batter into the prepared muffin tin, filling each cup about ¾ full.
Cinnamon Brown Sugar Topping
In a small bowl, make the crumb topping by mixing the brown sugar, cinnamon, flour, and butter. Use a fork (or your fingers) to combine until the mixture resembles coarse crumbs.
Sprinkle the crumb topping evenly over the muffins.
Bake for 18–20 minutes until golden brown, or until a toothpick inserted into the center of a muffin comes out clean.
Allow to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.
Notes
Optional: add 1 cup of chocolate chips to the banana batter before spooning into muffin tin.Can I use frozen bananas for this recipe? Yes! Just make sure they’re fully thawed and drained of any excess liquid before mashing. This helps prevent overly wet batter.What’s the best way to mash bananas? A fork works fine, but for ultra-smooth banana texture, use a potato masher or even a hand mixer.Can I make these muffins gluten-free? Absolutely. Swap the all-purpose flour for a 1:1 gluten-free baking flour blend. Be sure to check that all other ingredients (especially baking powder) are gluten-free as well.What if I don’t have muffin liners? No problem. Just spray your muffin tin well with nonstick spray or brush with melted butter to prevent sticking.