Combine the rolled oats, protein powder, chia seeds, and salt in a 16-ounce glass jar or airtight container.
Stir or whisk the dry ingredients together to ensure the protein powder is evenly distributed and free of clumps.
Add the almond milk, Greek yogurt, and vanilla extract to the container.
Stir the mixture vigorously with a spoon until the yogurt is fully integrated and the dry ingredients are completely submerged.
Seal the container with a lid and place it in the refrigerator for a minimum of 6 hours, or overnight, to allow the oats and chia seeds to hydrate.
Remove from the refrigerator and stir once more before serving, adding an extra splash of milk if a thinner consistency is desired.