Step 1: In a mason jar or airtight container, combine the milk, yogurt, maple syrup, vanilla extract, and salt. Stir well until the sweetener is fully incorporated.
Step 2: Add the rolled oats and chia seeds to the liquid mixture. Stir vigorously to ensure the chia seeds are not clumping and every oat is submerged.
Step 3: Gently fold in the blueberries. If using fresh berries, you can press a few against the side of the jar to release some juice.
Step 4: Secure the lid on the container and place it in the refrigerator for at least 6 hours or overnight.
Step 5: In the morning, give the blueberry overnight oats a good stir. If the mixture is too thick, add a splash of extra milk to reach your desired consistency. Top with extra berries or nuts if desired and enjoy cold.