Place the rolled oats, protein powder, chia seeds, cinnamon, and sea salt in a mason jar or any container with a lid. Stir the dry ingredients so they are evenly mixed.
Pour in the almond milk, then add the cashew butter, maple syrup, and vanilla extract. Stir well until the mixture looks smooth and everything is fully combined.
Mix in the mini chocolate chips so they spread evenly through the oats.
Close the container and place it in the refrigerator for at least 4 hours or overnight so the oats can soften and thicken.
Before eating, stir the oats again. If the mixture feels too thick, add a small splash of milk. Finish with extra chocolate chips or a drizzle of nut butter if desired.