Oatmeal is the perfect breakfast food: filling, inexpensive and healthy. But hot oatmeal in the hot, sticky summer? Not so much. That is where overnight oats come to play. Overnight oats are a cold, mueslie-type cereal. You prepare them the night before for a quick and easy breakfast. The star ingredients in this recipe are peanut butter and bananas. The peanut butter adds protein and healthy fats to help keep you full throughout your morning.