Preheat your oven to 350°F and grease a 9x13-inch baking dish.
Spread the lemon pie filling evenly across the bottom of the dish.
Sprinkle the lemon cake mix evenly over the pie filling.
Drizzle the melted butter evenly across the top.
Bake for 35 to 40 minutes, until the top is golden and bubbly.
Let it cool slightly before serving warm, ideally with vanilla ice cream or whipped cream.