Preheat oven to 375 degrees F. Line a 12 ct muffin pan with muffin cups (or opt to grease the cups with a thin layer of butter or coconut oil, or even cooking spray).
In the bowl of your KitchenAid mixer, cream the butter and sugars until well blended.
Add the bananas, eggs and sour cream and blend well until the mixture is free of lumps.
Add the flour, cinnamon and baking soda, and mix just until combined.
Fill muffin cups 2/3 full with batter.
Bake at 375 degrees F for 8 minutes. Reduce heat to 350 and continue to bake for 12 minutes or until muffins are browned.
Remove from the oven and allow to cool before enjoying.
Store tighly covered at room temperature up to 48 hours, or refrigerate for longer storage.