Add oats, chia seeds, salt, and 3 cups water to a medium bowl or container with a lid (whatever you want to store it in!). Mix until combined and let sit in the fridge overnight.
The next morning, the oats and chia should have soaked up most of that water with some water still remaining. If it’s too dry, just add more water. Stir in the yogurt, nut butter, and cinnamon (if using) until combined. If too thick or not mixing easily, add more water and mix again (or see below).
To get it ultra-creamy, you can add a few scoops of the chia/oats to a blender with the yogurt and nut butter (and some water if needed), blend until smooth, and stir it back into the oats.
Your chia oat base is complete! Stir in any sweetener, if you’d like. Thin it out with more water if it’s too thick for your liking. Serve cold or gently warm it up on the stove or in the microwave (if warming up, you may need to add some extra water). Top with your favorite toppings.