6 large eggs, at room temperature
1/4 teaspoon cream of tartar
1 tablespoon Grand Marnier liqueur
2 tablespoons water
4 tablespoons sugar
6 oz. of bittersweet chocolate (62 percent to 70 percent cocoa mass), finely chopped
4 tablespoons butter, small dice at room temperautre
The timing of this recipe is important. You want to have the egg whites whipped and your egg yolk/chocolate mixture ready at about the same time.
Separate the eggs and place the whites in the bowl of your mixer along with the cream of tartar (to lend stability to your whipped whites.) In another bowl, combine only four of the yolks (discard the other two or make a snack), water, Grand Marnier, and half the sugar.
Place a small pan of water to boil on the stove over which you will cook the egg yolk mixture and, later, finish melting the chocolate. Be sure that the bottom of the mixing bowl containing the yolk is not able to touch the surface of the water in the pan. Start to beat the egg whites in the mixer on medium-high speed. As the whites start to come to soft peaks add the remaining half of sugar to the bowl and maintain beating until stiff peaks form. Place the egg yolks over the water bath and whip steadily until the yolk mixture lightens in color and thickens to the consistency of a thick foam.
Remove from the heat and add the butter and chocolate, and stir thoroughly until fully incorporated. You may have to put the bowl over the water bath for a few seconds more to insure that the chocolate melts. However, don't leave on too long or the eggs could scramble and the chocolate seize. When the chocolate mixture is ready it will be smooth and have a rich, glossy sheen.
Gently fold the chocolate into the whites in three stages and be sure that the two masses combine entirely. Pour into the desired serving dish and refrigerate for at least 4 hours (I prefer overnight.)