In a clean mason jar, put together the rolled oats, cashew milk, and almond-based yogurt. Mix properly with a spoon.
Add in the chia seeds, making sure that it's mixed evenly with the rest of the ingredients.
To sweeten the mixture, add in the stevia extracts. Start with one tablespoon, then add some more as desired.
Top the mixture with the ripe bananas. You may mash them, but we generally prefer them chopped, to give the mixture a chunkier texture.
Sprinkle the mixture with the chopped walnuts.
Lastly, add in the cinnamon and the nutmeg. Adjust the amount as needed.