Preheat oven to 350 degrees F (175 degrees C). Lightly grease 24 muffin cups.
In a bowl, cream together the butter, sugar, and vanilla. Mix in banana and sour cream. Stir in the eggs. In a separate bowl, mix the flour, baking powder, and baking soda. Mix dry ingredients into the banana mixture until evenly moist. Fold in chocolate chips. Transfer batter to the prepared muffin cups, filling each cup about 3/4 full.
Bake 25 minutes in the preheated oven, or until a knife inserted in the center of a muffin comes out clean.