1. Combine the Dry Ingredients: In a medium-sized jar or container with a lid, add the rolled oats, chia seeds, ground cinnamon, and a pinch of salt. Stir these dry ingredients together briefly to ensure they are well combined. This helps distribute the cinnamon evenly.

2. Add the Wet Ingredients: Pour in the milk and unsweetened applesauce. If you’re using maple syrup or honey for sweetness, add it now.

3. Stir Thoroughly: Use a spoon to stir all the ingredients together very well. Make sure there are no clumps of oats or chia seeds sticking to the bottom or sides of the container. A good stir now prevents a lumpy texture later.

4. Fold in the Diced Apple: Gently fold in the finely diced apple pieces. You want them distributed throughout the mixture so you get a bite of apple with each spoonful.

5. Cover and Chill: Securely place the lid on your jar or container. Transfer it to the refrigerator and let it chill for at least 4 hours, but ideally overnight. The longer it chills, the thicker and creamier it will become.

6. Check Consistency and Serve: The next morning, remove the overnight oats from the refrigerator. Give them a quick stir. If they are too thick for your liking, you can add a splash more milk to reach your desired consistency.

7. Optional Toppings: Serve cold, adding any desired toppings like extra diced apple, a sprinkle of cinnamon, chopped nuts, or a drizzle of maple syrup.