Grab four mason jars or any airtight containers you have on hand — wide-mouth pint jars work perfectly for this. In a large mixing bowl, combine the rolled oats, chia seeds, ground cinnamon, ground nutmeg, and salt, and give everything a good stir so the dry ingredients are evenly mixed together.

Pour in the milk, Greek yogurt, maple syrup, and vanilla extract, then stir the whole mixture thoroughly until everything is well combined and no dry oat pockets remain at the bottom of the bowl. You want a creamy, even consistency throughout.

Divide the mixture evenly among your four jars, filling each one about three-quarters of the way full to leave room for your toppings later. Give each jar a little stir once more just to make sure the oats and chia seeds are distributed evenly.

Seal the jars tightly with their lids and place them in the refrigerator for at least 8 hours, or overnight. The oats will absorb the liquid during this time and thicken up into a pudding-like texture that's thick and creamy.

When you're ready to eat, pull a jar from the fridge and give it a good stir. If the oats feel too thick for your preference, just splash in a little extra milk and stir to loosen them up to the consistency you like. Top each jar with your choice of fresh berries, sliced banana, a sprinkle of chopped nuts, or a drizzle of extra maple syrup, and enjoy straight from the jar!