For each drink:
Separate egg whites and yolks. In a large mixer, beat yolks until thin, transfer to another bowl. Clean mixer and add the egg whites and cream of tarter, beat until stiff. Add powdered sugar and fold in yolks. Mix until batter is thick, but light.
In a pre-heated mug, add 1 heaping ladle of batter. Add rum and cognac. Top with hot water and dust with freshly grated nutmeg. Serve with a paddle or spoon.
Hint:
At home I use a Kitchen-Aid 4.5 Quart Capacity Tilt-Head Mixer for making the batter.
