In a large mixing bowl or container, combine the oats, blueberries, milk, chia seeds, and maple syrup.
Stir thoroughly until all ingredients are evenly incorporated.
For naturally purple overnight oats, blend ½ cup of the blueberries with the milk until completely smooth.
Mix the blueberry milk with the oats, chia seeds, maple syrup, and remaining blueberries.
Cover the container tightly.
Refrigerate for at least 4 hours, preferably overnight.
The oats will absorb the liquid and become thick and creamy.
Divide between two jars or serving bowls.
Add your favorite toppings before serving.