Preheat your oven to 400°F. Spray a muffin tin lightly with oil or line with muffin liners.
Combine all ingredients except the cranberries into the container of a high powered blender. Pulse to break up banana pieces then blend on medium-high for 45 seconds. Batter should be thick and smooth with small, visible pieces of oats throughout.
Stir dried cranberries into the batter by hand.
Pour batter evenly into 12 prepared muffin liners and bake for 18-19 minutes.
Cool muffins in pan for 5 minutes, then remove to a cooling rack.