Preheat oven to 375°F.Spray baking dish with nonstick cooking spray.Pour blueberries into the baking dish and spread them in an even layer.
In a medium bowl, mix the oats, flour, cinnamon, and salt.Pour in the maple syrup and mix to combine.Cut in the cubed butter using a pastry cutter or 2 knives until crumbled.
Sprinkle the mixture over the blueberries.Bake for 25 minutes or until golden on the top.
Store leftovers in an airtight container in the refrigerator for up to 4 days.