Preheat oven to 350 F and lightly grease a 9 x 13 inch baking pan.
Dump both cans of pie filling into the pan and spread it evenly so that no part of the bottom of the pan is visible. Use a spoon or measuring cup to dust the pie filling with the cake mix, covering it evenly.
Add the butter in pats to cover the cake mix, then sprinkle in the fresh blueberries.
Bake for 45 minutes, or until the top looks golden brown. Serve warm on its own or with a scoop of vanilla ice cream. Enjoy!
If you can't find 21 oz cans of blueberry pie filling, feel free to use ones that contain slightly more or less. This recipe is flexible!