Preheat the oven to 350°F and line a 9×13-inch baking pan with parchment paper, ensuring the edges are well covered to prevent sticking.
In a large mixing bowl, combine the entire contents of the angel food cake mix with the lemon pie filling. Stir vigorously until the mixture becomes foamy and smooth in texture.
Pour the batter into the prepared pan, spreading evenly to the corners.
Place the pan in the oven and bake for 30 to 40 minutes. Begin checking at the 30-minute mark, but continue baking until the surface is golden and firm to the touch with no wobble in the center.
Remove from the oven and allow the bars to cool completely in the pan before slicing into squares for serving.