Preheat oven to 375 degrees.
Line 12 muffin tins with cupcake liners.
Stir the flour, baking soda, salt, and cinnamon together in a bowl.
Put the bananas in the bowl of your mixer. Beat until just mashed.
Beat in the melted butter, brown sugar, egg, vanilla extract, and milk until just mixed.
Add the dry ingredients to the mixer. Mix until just combined. (Do not overmix)
Fold in the pecans and chocolate chips.
Spoon the batter into the lined muffin tins.
Bake for 20 to 24 minutes, or until set and lightly brown.
Let cool. Enjoy!