Preheat oven to 350 degrees.
Line a standard 12-cup muffin tin with baking cups.
In a medium bowl, whisk together flour, baking powder, salt, and cinnamon.
In a separate bowl, whisk together banana, sugar, egg, butter, and milk.
Stir wet ingredients into dry ingredients
Stir in mini chocolate chips.
Divide batter evenly between prepared cups, adding a scant 1/4 cup to each.
Bake until tops spring back when lightly touched, about 20 minutes.
Cool in pans 5 minutes, then remove to wire rack to cool completely.