Place the rolled oats, chia seeds, cinnamon, and salt in a large sealable container. Stir to combine.

Add the milk, maple syrup, and vanilla extract. Stir again until everything is evenly mixed.

Fold in the frozen blueberries.

Let the mixture sit for about 10 minutes, then stir once more. This helps prevent the chia seeds from clumping together.

Cover and refrigerate overnight.

The next morning, scoop out a serving and enjoy. If the oats are thicker than you like, simply stir in an extra splash of milk.