Preheat oven to 350°F (175°C) or the temperature on the cake mix box. Grease a 9×13-inch baking dish with butter, cooking spray, or line with parchment paper.

In a large bowl, add the angel food cake mix and lemon pie filling. Stir until smooth and lump-free.

Pour the batter into the prepared baking dish, spreading it evenly. Bake for about 25 minutes or as specified on the cake mix box, until golden brown and a toothpick comes out clean.

Let the bars cool in the pan on a wire rack for 10 minutes. Once cooled, cut into squares or rectangles, wiping the knife between cuts for clean slices.

Optional: Dust with powdered sugar or serve with whipped cream. Arrange on a platter or plates for serving.