In a large mixing bowl, gather rolled oats, your choice of milk, chia seeds, maple syrup, cinnamon, and vanilla extract. Stir vigorously for about a minute until everything is well combined.

Let the combined mixture sit for 5 minutes at room temperature to allow the chia seeds to absorb the liquid and swell.

Divide the mixture evenly into individual jars or containers, filling about three-quarters full.

Cover each jar tightly with a lid or plastic wrap and place them in the refrigerator. Chill for at least 4 hours, ideally overnight.

When ready to enjoy, stir each jar well and add a splash of milk if needed. Top with fresh fruit or nuts before serving.