Combine chopped apples, maple syrup or brown sugar, cinnamon, and sea salt in a small saucepan. Cook on low heat for about 10 minutes, stirring occasionally until apples are soft. Increase heat to medium, cooking for an additional 2-3 minutes until the sauce thickens. Set aside.
In a bowl, mix almond milk, chia seeds, vanilla, cinnamon, nutmeg, and nut butter until creamy. Stir in the oats until well combined.
Divide the oat mixture into two jars or airtight containers. Layer each container with a quarter of the cooked apples, add half the oat mixture, and top with the remaining apples. Optionally, add chopped nuts. Cover and refrigerate for at least 6 hours or overnight.
Enjoy cold, at room temperature, or warm slightly if preferred. For extra variety, you can add toppings like granola or coconut yogurt before serving.