In a large glass jar or container with a lid, combine the oats, milk, yogurt, maple syrup, chia seeds, and salt. Stir to combine.
To make flavored oats, add any of the suggested flavor combination ingredients or add your own mix-ins as desired and stir to combine. Cover and refrigerate for at least 8 hours or up to 5 days.
When ready to eat, stir the oats again and thin with more milk, if needed. Add any additional toppings or flavorings as desired.
Notes
If your oats have thickened up more than you prefer, stir in some extra milk to thin the consistency. This can happen if you used thicker or drier mix-ins, or if your oats have been chilling for a few days.
The nutrition information is for the base oats only, without mix-ins.