Beat egg whites on high speed until soft peaks form, 3 to 4 minutes. Gradually
add sugar, beating until stiff but not dry. Blend in juice. Coat 9-inch pie pan
with nonstick cooking spray. Spoon meringue mixture into pan, and with a tablespoon,
push mixture up around edges to form pie shell. Bake at 200 degrees F for 2 hours.
Filling: Beat egg yolks with sugar, lemon zest and juice until light in color
and slightly thickened. Cook, stirring, in top of double boiler set over, but not
touching, simmering water until thickened, about 10 minutes.
Remove from heat and cool thoroughly. Fold in half of whipped cream. Turn into
Meringue Crust and refrigerate at least 2 hours to set.
Fold powdered sugar into remaining whipped cream and spread over chilled pie.