Preheat Oven: Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking pan with non-stick spray or a light coating of butter.

Add Pineapple: Pour the crushed pineapple with its juice evenly into the bottom of the prepared baking dish. Spread it into a single layer so the fruit covers the entire pan.

Top with Cake Mix: Sprinkle the dry yellow cake mix evenly over the pineapple layer. Do not stir — simply cover the fruit completely with the dry cake mix like a blanket.

Add Butter: Pour the melted unsalted butter slowly and evenly over the cake mix. Try to cover as much of the top as possible so the cake mix will absorb the butter and bake up with a golden crust.

Bake: Place the pan in the preheated oven and bake for 45–50 minutes, or until the top is golden brown and the pineapple filling is bubbly around the edges.

Cool Slightly: Remove from the oven and let the cake cool for about 10–15 minutes before serving. This helps the dessert set slightly for cleaner slices.