In a large bowl, stir together oats, milk, protein powder, sweetener, vanilla, cinnamon, and salt until well combined.
Ensure the protein powder is fully dissolved for a smooth consistency.
Divide the mixture evenly among five 8-ounce jars. Screw on lids and refrigerate overnight or for up to 5 days.
Tips:
If the mixture becomes too thick after adding the protein powder, add a splash of extra milk before refrigerating.
Customize with toppings like fresh fruit, nuts, or seeds before serving!