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 pockets remain.
02 - Cover the container tightly and refrigerate for at least 8 hours or overnight to allow oats to soften and absorb the liquid.
03 - In the morning, stir the oats thoroughly. Add a splash of milk if the mixture is too thick for your preference.
04 - Top with banana slices, chopped nuts, and fresh berries or apple slices if desired. Serve chilled.