Preheat oven to 350℉. Spray a 7x11-inch or 9x9-inch baking pan with cake release or non-stick spray.
Pour the can of strawberry pie filling into the bottom of your dish and spread it evenly with a spatula. Spread the blueberries out over the pie filling.
Lay the cubes of cream cheese on top of this mixture.
Add the cake mix and butter to a large bowl. Cut the butter into the cake mix with a pastry blender or fork. When mixed, it should resemble wet sand. Try not to have large clumps of butter or any dry cake mix. It takes a few minutes to mix this correctly. Spread this mixture evenly over the pie filling.
Bake at 350℉ for 40 to 45 minutes or until the top is golden brown.