In a bowl, combine the rolled oats, almond milk, and ground cinnamon.
Stir well until everything is evenly mixed.
Cover the bowl or transfer the mixture to a mason jar with a lid.
Refrigerate for at least 2 hours, preferably overnight.
For a layered Apple Cinnamon Overnight Oats presentation, spoon a few tablespoons of soaked oats into the bottom of a jar.
Add a layer of flaxseed (or chia seeds) followed by diced apple.
Continue layering oats, raisins (or dates), and apples until all ingredients are used.
Finish with chopped walnuts and a light sprinkle of cinnamon.
Serve chilled straight from the refrigerator.