You can prepare the muesli in two main ways: Cold: simply pour muesli into a bowl, add milk, and serve. For a creamier texture reminiscent of overnight oats, combine muesli and milk in an airtight container and refrigerate for 20 minutes to overnight. Hot: simmer muesli and milk in a pot over medium-high heat for 3-4 minutes, or microwave in a bowl for 1 minute, then let it stand for 2 minutes before serving.