In a mixing bowl or mason jar, combine the rolled oats and chia seeds.
Add the milk, Greek yogurt, honey (or maple syrup), vanilla extract, and a pinch of salt.
Stir well until everything is evenly combined.
Let the mixture sit for about 5 minutes, then stir again to prevent the chia seeds from clumping.
Cover and refrigerate for at least 6 hours or overnight.
Before serving, give the oats a good stir. If they're thicker than you'd like, add a splash of milk and mix well.
Top with your favorite fruits, nuts, seeds, or granola, and enjoy!