Beat reconstituted powdered whites until frothy. Gradually beat in remaining 2 tablespoons sugar and cream of tartar until stiff, moist peaks form. Fold 1/4 of the beaten whites into egg yolk mixture. Fold in remaining whites. Refrigerate, covered, until mixture just begins to mound when spooned, 1 1/2 hours. Spoon into six 8-ounce serving glasses; cover and refrigerate at least 1 hour, until set. Garnish with nutmeg.