Lightly spray 9x13-inch baking dish with nonstick cooking spray.
Sprinkle cake mix evenly over the bottom of the prepared baking dish. Top cake mix with layer of blueberries. Sprinkle sugar on top of blueberries.
Pour water over blueberries and cake mix. Use a spoon or spatula to lightly stir water into the cake mix, ensuring most of the water goes to the bottom.
Place butter on top of the cobbler mixture and bake for 40 - 45 minutes, or until the cake mix has set.
Video
Notes
Test blueberries before adding sugar. If the blueberries are tart, add an additional 2 tablespoons of sugar in step 3.Nutrition information is calculated using only 2 tablespoons of sugar and does not include toppings such as ice cream or whipped cream.Optional Garnishes: Fresh blueberries, mint sprigs, lemon zestAlternative method: Pour cake mix into 9x13 baking dish. Add water and lightly stir. Top with blueberries, butter, and sprinkle with sugar. Bake as directed.