1/2 cup granulated sugar1 box (about 15.25 ounces) yellow cake mix, dry1/2 cup (1 stick) unsalted butter, melted
Directions
Preheat your oven to 350°F (175°C). Lightly butter or spray a 2-quart oven-safe white ceramic casserole dish; an 8×8-inch or similar size works well.
Dump the frozen raw whole blueberries straight into the prepared casserole dish. They should be evenly spread in a single, fairly even layer. It’s fine if you can see ice crystals clinging to the berries—that’s exactly how you want them.
Sprinkle the granulated sugar evenly over the frozen blueberries. Don’t stir; just let the sugar sit on top so it can melt down into the berries as they bake.
Evenly sprinkle the dry yellow cake mix over the sugared blueberries, covering the surface from edge to edge. Again, do not stir. You want a loose, even blanket of dry mix on top.
Slowly drizzle the melted butter over the entire surface of the dry cake mix, trying to moisten as much of the top as you can. It’s fine if a few dry spots remain; they’ll still bake up into a nice, slightly crisp topping.
