1 baked 8 inch pie shell (pastry or crumb)
1 1/3 c. (15 oz.) can condensed milk
2 eggs, separated
1/2 c. juice of key limes
Grated rind of one lime (optional)
2 egg whites
4 tbsp. sugar
1/4 tsp. cream of tartar

Blend condensed milk, lime juice, lime rind and egg yolks with electric mixer at medium speed until light. Beat egg whites until fluffy and fold into lime mixture. Pour into pie shell.

Add cream of tartar and sugar to egg whites and beat until stiff enough to peak. Pile lightly on filling and bake in slow oven (325 degrees) about 15 minutes or until lightly browned. Cool before serving.