Preheat the oven to 350℉. Grease the muffin tin(s) with non-stick spray or line with muffin liners.
In a large bowl using an electric handheld mixer, cream the softened butter, sugar, and brown sugar at medium speed for 1 minute. Add the eggs, vanilla, mashed bananas, and sour cream and continue beating for 30 seconds until fluffy.
½ cup salted butter, ¼ cup white sugar, ½ cup brown sugar, 2 eggs, 1 teaspoon vanilla extract, 1 ½ cups ripe mashed bananas, ½ cup sour cream
Add the flour, baking powder, baking soda, and salt and mix at low speed just until incorporated. Fold in the chocolate chips.
1 ½ cups all-purpose flour, 1 teaspoon baking powder, 1 teaspoon baking soda, ½ teaspoon salt, 1 cup semisweet chocolate chips
Scoop the batter into the prepared muffin tin(s), filling each cup (18 in total) about ¾ full with batter. Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean. Let cool in the muffin tin for 10 minutes before transferring to a wire rack to finish cooling. Enjoy!
Notes
You could use unsalted butter with an additional ¼ teaspoon of salt added to the dry ingredients.