In a small saucepan over medium heat, combine fresh or frozen blueberries with maple syrup, cooking for about 1 minute until softened. Remove from heat and let cool before refrigerating for at least 30 minutes.

In a mixing bowl, combine rolled oats, chia seeds, and your choice of water or milk. Add maple syrup, Greek yogurt, vanilla extract, and a pinch of salt. Stir until fully combined.

Cover the bowl and refrigerate for a minimum of 3 hours or overnight for best results.

To serve, layer the chilled blueberry mixture at the bottom of a mason jar, followed by a scoop of the overnight oats. Add toppings if desired.