Line a bowl (with an approximately 8” mouth) with plastic wrap and fill with softened ice cream. Leave about 1” space at the top and cover with sponge cake. Wrap in plastic and freeze for at least 4 hours, or overnight. Remove plastic from cake and turn ice cream and cake out onto a platter. Remove plastic from ice cream. In a small bowl, whip egg whites and cream of tartar until it starts to thicken. Gradually add sugar while whipping, until the whites form soft peaks. Use immediately. Pipe meringue attractively over the entire surface of the ice cream and exposed cake. Using a culinary torch, quickly sweep the surface of the meringue with the flame until it turns a golden brown. Serve immediately. Serves 12.