Muesli ( MEWZ-lee) is a cold Swiss breakfast dish, the primary ingredient of which is rolled oats. Most often, it is set to soak overnight and eaten the next morning. Additional ingredients, such as grains, nuts, seeds, and fresh or dried fruits, are added, along with milk or cream, a squeeze of citrus juice, and honey to add sweetness. Yoghurt or other mammal or plant milk products are now commonly added to both homemade and commercially packaged muesli recipes.

Developed around 1900 by Swiss physician Maximilian Bircher-Benner for patients in his hospital, it is now eaten as a standard breakfast dish, like a breakfast cereal, and in Switzerland also for supper as Birchermüesli complet – muesli with Café complet (milk coffee, accompanied by bread, butter and jam (Butterbrot)).

In addition to being prepared raw, muesli can be toasted. Muesli can also be processed further by adding sweetener and oil to bind the ingredients together and baked to produce granola.