Preheat the oven to 375 degrees Fahrenheit and spray a muffin liner with pan spray and, if desired, line it with muffin liners.
Add the mashed bananas, egg, sour cream, vanilla, butter, oil, brown sugar, and granulated sugar to a large bowl and beat with a hand mixer until combined.
Add the flour, baking soda, baking powder, and salt to a medium bowl and whisk until combined. Add the dry ingredients to the wet ingredients and mix until just combined.
Fold in the chocolate chips by hand. Scoop the batter into the prepared muffin pan until each muffin well is ⅔ of the way full.
Bake for 18-22 minutes, until a toothpick comes out clean from the center of a muffin. Let the muffins cool for 5-10 minutes before serving.