In large bowl, mix powdered egg whites and 1/2 cup warm water; let stand.
In large metal bowl, combine yolks, 14 cup each of the sugar and the cream and the butter. Place bowl in saucepan of simmering water. Cook, stirring constantly, until temperature reaches 160 degrees F on an instant-read thermometer, about 4 to 7 minutes. Remove bowl from pan.
Beat remaining 3/4 cup cream with 1/4 cup sugar, rum, brandy, cinnamon, nutmeg, cloves and vanilla until stiff peaks form. Fold into egg yolk mixture.
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.