1.
Heat oven to 275°F. Spray 9-Inch pie pan with non-stick cooking spray.
1.
In large bowl, combine egg whites, salt and cream of tartar. Beat at medium-low speed until egg whites are frothy. Increase speed to medium. Add 1 cup of the sugar; continue beating until stiff peaks form. Spread evenly into pan.
2.
Bake 1 hour. Cool on wire rack.
1.
Beat egg yolks at medium speed in another large bowl until thick and lemon-colored. Stir in remaining 1/2 cup sugar, orange juice, orange zest, lemon juice, and lemon zest. Pour mixture into small saucepan. Cook on low heat until thickened; cool.
2.
Spread 1 cup of the whipped topping over pie shell. Spread citrus filling gently over topping; top with remaining 1 cup whipped topping. Refrigerate 4 hours before serving. Store in refrigerator.