Preheat oven to 350 degrees Fahrenheit. Line 1 1/2 muffin pans with cupcake wrappers or spray with nonstick spray.
In a large, microwave safe bowl, melt butter
Add in granulated sugar to melted butter
Using a fork, smash bananas into the sugar and butter until most of the chunks are gone.
Stir in sour cream, milk, and eggs.
Add in vanilla extract
Stir in baking soda, baking powder, and flour.
Stir in chocolate chips if desired.
Scoop batter into muffin pan. Fill cupcake liners 2/3 of the way full with batter.
Bake at 350 degrees for 20-25 minutes. Allow to cool and enjoy!