Prepare the Oven: Set the oven to 350 degrees Fahrenheit. Line a muffin pan with paper liners or lightly grease each cup. This step helps the muffins bake evenly and lift easily.
Mix Dry Ingredients: Add flour, baking soda, salt, and cinnamon into a bowl. Stir well so the leavening and spice spread evenly through the flour.
Mash the Bananas: Place ripe bananas into another bowl. Mash until mostly smooth with a few small lumps. Those bits add texture and deeper banana flavor.
Blend Wet Ingredients: Stir brown sugar, granulated sugar, melted butter, egg, and vanilla into the mashed bananas. Mix until smooth and glossy.
Combine Batter: Pour the wet mixture into the dry ingredients. Stir gently until just combined. Fold in chocolate chips slowly so the batter stays light.
Fill Muffin Cups: Spoon batter into each cup, filling about three quarters full. Sprinkle a few extra chocolate chips on top if you like.
Bake Until Set: Place the pan in the oven and bake for eighteen to twenty two minutes. The tops should spring back when touched gently.
Cool Slightly: Let the muffins rest in the pan for five minutes. Transfer to a rack so steam escapes and the bottoms stay soft.
