Preheat oven to 350°F. Line a 12-cup muffin tin with liners.

To a medium bowl, add sugar and butter. Mix until combined.

Add bananas, milk, eggs, and vanilla. Mix well.

Add flour, baking powder, and salt, mixing until just incorporated. Fold in cranberries.

Evenly divide the batter between the 12 muffin cups, filling each about ¾ full.

Bake for 27-30 minutes, or until an inserted toothpick comes out with a few crumbs, but no wet batter.

Let the muffins rest for about 5 minutes in the muffin tin before removing them and transferring to a wire rack.