In a sealable glass jar or container, combine the rolled oats, protein powder, chia seeds, cinnamon, and salt.
Add the almond milk, Greek yogurt, and vanilla extract.
Stir thoroughly with a spoon or seal the jar and shake vigorously until the protein powder is fully integrated and no dry pockets remain.
Incorporate the dark brown sugar into the mixture.
Seal the container tightly and refrigerate for at least 4 hours, or overnight for optimal texture.
Before consuming, stir the oats once more and add an additional splash of milk if a thinner consistency is preferred.