In a medium mixing bowl, add rolled oats, chia seeds, ground cinnamon, and vanilla extract. Stir thoroughly until well combined.

Pour in milk and maple syrup into the dry mixture. Stir until well incorporated.

Divide the oat mixture into two glass jars, shaking gently to settle the oats.

Seal jars and refrigerate for at least 4 hours, preferably overnight.

Before serving, stir and add a splash of milk if the mixture is too thick.

Serve cold or warm in the microwave, adding toppings like nuts or fruits.