Preheat oven to 350 degrees F.

Prepare cake batter as directed on package for 2 (9-inch) round layers, blending half the lemon zest into batter.

Pour batter into prepared pans.

Bake as directed on package.

Cool cakes in pans for 10 minutes.

Invert onto wire racks and gently remove pans.

Cool cakes completely.

Mix cornstarch and 2 Tbsp. sugar in a medium saucepan.

Gradually stir in water.

Bring to a boil on medium heat and cook for 8 minutes, stirring constantly.

Remove from heat.

Add dry gelatin mix and stir for 2 minutes until completely dissolved.

Stir in lemon juice and remaining zest.

Refrigerate for 40 minutes or until slightly thickened, stirring occasionally.

Preheat oven to 450 degrees F.

Place 1 cake layer on parchment paper-covered baking sheet.

Beat egg whites and cream of tartar in a small bowl with a mixer on high speed until foamy.

Gradually beat in remaining sugar until stiff peaks form.

Spread meringue onto top of the cake layer on prepared baking sheet.

Bake for 5 to 7 minutes or until meringue is golden brown.

Place remaining cake layer on serving plate.

Spread with gelatin mixture and then COOL WHIP.

Top with meringue-topped cake layer.

Serve and enjoy!