In a medium mixing bowl or a large jar, add the old-fashioned rolled oats, milk, cinnamon, maple syrup, and vanilla extract. Stir the mixture vigorously for about 1 minute until all the ingredients are well blended.

If you desire extra creaminess, scoop in the Greek yogurt at this stage. Gently fold it into the oat mixture using a spatula.

Once everything is mixed, cover the bowl or jar tightly. Place it in the refrigerator for a minimum of 4 hours, or ideally overnight.

When ready to enjoy, take the jar of oats from the fridge and give it a good stir. Serve in bowls or jars, topping with cinnamon, fresh fruit, or nuts.