10 oz. (10 sq.) sweet or bittersweet chocolate
6 tbsp. water
2 egg yolks
1 tbsp. sugar
3 tbsp. creme de cacao or any other chocolate-flavored liqueur
2 tbsp. dark rum
1 1/2 c. heavy cream
1 (10") baked tart shell, purchased or homemade
Whipped cream for garnish (optional)

1. Combine the chocolate and water in a saucepan. Place in a skillet of barely simmering water and heat, stirring as necessary, until the chocolate melts.

2. Meanwhile, put the egg yolks and sugar in the bowl of an electric mixer (or another heatproof bowl). Add the creme de cacao and set the bowl in another skillet of barely simmering water. Beat vigorously with a wire whisk until the sauce becomes thick, like a stiff custard. Remove from the hot water and let cool briefly.

3. Let the melted chocolate cool slightly (if it is too hot when added to the sauce, it will tend to overcook the eggs). Add the chocolate to the sauce and fold it in with a rubber spatula. Beat in the rum.

4. Whip the cream until stiff. Fold into the chocolate mixture.

5. Spoon the chocolate filling into the baked tart shell. Cool briefly, then chill in the refrigerator or freezer, depending on the time available.

6. Garnish with additional whipped cream, if desired. 8 or more servings.