01 - In a medium bowl or jar, combine the oats, milk, Greek yogurt, brown sugar, cinnamon, and vanilla extract. Stir well until fully incorporated and no dry oats remain visible.
02 - Cover the container tightly with a lid and refrigerate for at least 8 hours, preferably overnight, to allow oats to soften and absorb the liquid.
03 - In the morning, stir the oats thoroughly. If the mixture appears too thick, add a splash of milk and stir again to reach desired consistency.
04 - Top with banana slices, chopped nuts, and fresh berries or apple slices if using. Serve chilled directly from the refrigerator.