Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with paper liners.

Mash the ripe bananas in a medium mixing bowl until mostly smooth with some chunks remaining.

Combine the mashed bananas with brown sugar, melted butter, eggs, vanilla extract, and milk, mixing until creamy.

In another bowl, whisk together flour, baking soda, salt, and ground cinnamon.

Fold the dry ingredients into the wet ingredients gently until just combined.

Divide the batter evenly into the prepared muffin cups, filling each about ¾ full.

Bake for 18-22 minutes until golden brown and a toothpick comes out clean.

Cool in the pan for 5 minutes before transferring to a wire rack to cool completely.