1 yellow cake mix
1 lg. pkg. lemon pie filling
2/3 c. sugar
1 tbsp. cornstarch
2 c. blueberries
Dash of salt
2/3 c. water

Bake yellow cake in jelly roll pan. Top with lemon pie filling. Cover with Cool Whip. Chill. Cook water, sugar, cornstarch and salt until thick and boiling. Add blueberries, return to boil. Chill. Serve cake with blueberry sauce on top.