Add the rolled oats, milk, unsweetened applesauce, ground cinnamon, and a pinch of salt to a mason jar or container with a lid. Add any optional add-ins at this point.
Stir everything together until well combined.
Cover with a lid and refrigerate for at least 4 hours, or overnight (8 to 12 hours) for best results.
In the morning, remove from the fridge and give it a good stir. If the oats are too thick, add a splash of milk and stir again.
Add your favorite toppings (granola, sliced apple, chopped nuts, nut butter) and enjoy cold, or microwave for 1 to 2 minutes if you prefer them warm.
Notes
Oat type: Use old-fashioned rolled oats for the best texture. Quick oats get too mushy. Steel-cut oats won't soften enough.
Sweetener: Taste before adding maple syrup or honey. The applesauce usually provides all the sweetness you need.
Meal prep: Make 4 to 5 jars on Sunday for the whole week. They keep for 3 to 4 days in the fridge.
Toppings: Add granola, nuts, and fresh fruit in the morning to keep them from getting soggy.
Warm option: Microwave for 1 to 2 minutes if you prefer a warm breakfast.