Mix everything thoroughly before chilling—do not leave ingredients layered, or the oats won’t soften properly. Best eaten cold, straight from the fridge. Store in an airtight container in the fridge for up to 5 days. Substitutions: use instant oats instead of rolled oats, any milk of choice instead of nonfat milk, and your preferred sweetener (stevia, maple syrup, honey, etc.). Frozen blueberries can be used in place of fresh.