01 -
Lightly coat a 9x13 inch baking dish with cooking spray to prevent sticking and facilitate cleanup.
02 -
Evenly spread half of the yellow cake mix into the prepared dish, using your hands or the back of a spoon to form a uniform layer that reaches all edges.
03 -
Spoon both cans of blueberry pie filling evenly over the cake mix layer, distributing fruit gently without disturbing the base.
04 -
Scatter the remaining cake mix evenly over the blueberry filling, avoiding thick piles to ensure an even bake.
05 -
Grate the very cold unsalted butter using a box grater to create small curls, then distribute the butter curls evenly across the surface and edges.
06 -
Bake in a preheated oven at 375°F (190°C) for approximately 40 minutes until the topping is golden brown and the filling bubbles at the edges. Monitor closely near end of baking to prevent over-browning.
07 -
Allow to rest for a few minutes to thicken the juices. Serve warm, optionally accompanied by vanilla ice cream for added creaminess.