Set the oven to 350°F (175°C) and grease a 9x13-inch baking dish using butter or nonstick spray. This keeps everything from sticking once it’s baked and golden.
Add the pineapple from both cans, juice included, and spread it evenly in the dish. The juice adds that extra moisture and sweetness that makes this cake so irresistibly gooey.
Evenly sprinkle the dry cake mix over the layer of fruit. No mixing needed, just try to cover everything in an even layer. Then, add a light sprinkle of brown sugar across the surface for a sweet, caramelized twist.
Cut the butter into slices and place them evenly over the top. As it bakes, the butter melts into the cake mix and creates a buttery, crisp topping.
Bake for 50 minutes, or until the top is golden and bubbly around the edges.
Let it cool just a bit before serving, then grab a spoon and enjoy the warm, tropical magic.