In a canning jar or bowl mix together the oats, cinnamon, brown sugar, and flax/chia seeds, if using. Stir in the milk, maple syrup, and diced apple. Seal with a lid or plastic wrap and place in the refrigerator for at least 8 hours.
In the morning, you can enjoy these oats cold, or warm them up if you prefer. Top with additional diced apple, cinnamon, and maple syrup if you'd like!
** Nutritional information is an estimate and may vary.