1 teaspoon cream of tartar
3 cups sifted powdered sugar
6 stks (1 ½ pounds) unsalted butter, softened and cut into pieces
1 cup (6 ounces) Crisco
(Lemon, orange or lime), liqueur (such as Grand Marnier, Kahlua, framboise, Frangelico, rum, brandy, and the like), or orange or rose flower water
Place egg whites and granulated sugar in a double boiler over medium heat.