Place the rolled oats and whey protein powder into a mason jar or airtight container.

Add the Greek yogurt, almond milk, chia seeds, and vanilla extract.

Stir vigorously with a spoon until the protein powder is completely dissolved and the mixture is uniform.

Seal the container and place it in the refrigerator for at least 4 hours or overnight.

Remove from the refrigerator and stir once more before serving; add a splash of water or milk if a thinner consistency is preferred.