Heat oven to 275 degrees. Grease 9-inch pie pan. In small bowl, beat egg whites (reserve yolks) with cream of tartar until frothy. Gradually add 3/4 cup sugar, beating continuously until stiff peaks form. Spread over bottom and sides of prepared pie pan. Meringue puffs up during baking, so spread only to top edge of pan. Bake for 60 minutes. Turn oven off. Leave crust in oven to cool and dry. In small saucepan, combine filling ingredients except whipped cream. Cook over low heat until thickened stirring constantly. Cool. Fold into whipped cream. Pour into meringue shell. Refrigerate overnight. If desired, garnish with thin lemon slices or grated lemon peel. 9-inch pie.