Preheat oven to 350F and prepare a 9x13 baking dish by spraying generously with non-stick spray and line with parchment if desired.
In a large mixing bowl, combine the lemon pie filling and the angel food cake mix. Mix until smooth. The mixture will be thick.
Pour the batter into the prepared pan and smooth evenly.
Bake for 25-28 minutes or until the top is golden-brown and the cake is set.
Remove from the oven and allow to cool for at least 15 minutes on a wire rack.
Sprinkle with powdered sugar and top with fresh lemon slices and serve.
Keep any leftovers in an airtight container at room temperature for up to three days.
ENJOY!
