In a jar with a tight fitting lid, stir together the oats, salt, and milk (plus the yogurt if making Version 2).
Secure the lid and refrigerate overnight (at least 4-5 hours).
In the morning, give the ingredients a final stir. Add additional milk or yogurt to thin out the consistency if desired. You can either enjoy the oats cold, or microwave until hot. (I recommend covering and microwaving for around 1 minute 15 seconds).
Add additional toppings if using (see notes). Overnight oats will keep in the refrigerator for up to 5 days.
Do not use instant oats with this recipe. Water can be technically substituted for the milk, but the results will be much less creamy so I don't recommend it unless maybe you're going for a savory version. For gluten-free overnight oats, make sure to purchase certified gluten-free rolled oats.Some optional topping ideas: