Lemon Curd Layer Cake
In a medium, heavy-bottomed saucepan, whisk together zest and juice, sugar, eggs, and cornstarch. Over medium high heat, cook mixture 4 to 5 minutes, whisking constantly, until thick and bubbly. Press though a fine mesh strainer into a bowl. Chill at least 1 hour. Place 1/3 of the chilled lemon curd in a mixing bowl and gently fold in the whipped topping. Set aside. With a long serrated knife, trim top of cake, if desired.