Preheat oven to 350°F and grease a 9x13-inch baking dish.
Spread the drained pears evenly in the bottom of the dish.
Sprinkle cinnamon over the pears.
Pour the dry cake mix evenly on top—don’t stir.
Drizzle melted butter evenly over the cake mix, trying to cover as much as possible.
Bake for 45–50 minutes, until golden and bubbly around the edges.
Let cool slightly before serving. Top with ice cream or whipped cream if you’re feeling fancy.