In a container or jar, combine the Greek yogurt, rolled oats, strawberry jam, and chia seeds if using. Stir the mixture thoroughly to ensure the ingredients are evenly distributed.
Cover the container and place it in the refrigerator to chill for at least 8 hours or overnight, allowing the oats to soften and the flavors to meld.
Cook's Note
Feel free to use any type of jam based on your preference, though strawberry is recommended for its balanced sweetness. Regular plain yogurt can be substituted for Greek yogurt, and flax seeds may be used in place of chia seeds.