Preheat your oven to 350°F and grease a 9×13-inch baking dish.
Pour the crushed pineapple with its juice evenly into the baking dish. Sprinkle the pecans and then the brown sugar evenly over the pineapple, and then sprinkle the dry yellow cake mix evenly on top.
Slowly drizzle the melted butter evenly over the cake mix. Bake for 45-55 minutes or until the top is golden and the pineapple is bubbling.
Allow the cake to cool for about 10 minutes before serving with optional ice cream or whipped cream.