Muesli is a cold Swiss breakfast dish, the primary ingredient of which is rolled oats. Traditionally, it is set to soak overnight and eaten the next morning. Additional ingredients, such as grains, nuts, seeds, and fresh or dried fruits are sometimes added, along with milk or cream, a small amount of citrus juice, and honey to add sweetness. Yoghurt, other milk products, or milk substitutes are now commonly added to both homemade and commercially packaged muesli recipes.

Rolled oats are a type of lightly processed whole-grain food. They are made from oat groats that have been dehusked and steamed, before being rolled into flat flakes under heavy rollers and then stabilized by being lightly toasted.