Lightly oil and chill a 2-quart soufflé dish, or furnish a 1-1/2 quart soufflé dish with an oiled aluminum foil collar.
In the top of a double boiler, over direct heat, scald the milk. In a mixing bowl, beat the eggs yolks. Pour the milk over the yolks in a steady stream, heating the mixture constantly. Return it to the top of the double boiler and set the pan over simmering water.
Add the sugar and salt. Cook the custard, stirring constantly, until it thickens and coats a metal spoon. Remove it from the heat.
Add the gelatin and alcohol, stirring until the gelatin is dissolved.
Stir in the orange zest. Transfer the mixture to a mixing bowl, allow it to cool, and then chill it until it just begins to set. This is the tricky part; if it chills too long, it will be lumpy.
With a rotary beater, beat the chilled mixture briefly to assure its smoothness. Fold in the whipped cream. Beat in one-fifth of the egg white; fold in the remainder. Using a rubber spatula, transfer the mixture to the prepared soufflé dish. Chill the soufflé for at least 6 hours, or until it is thoroughly set.
If you wish to offer a sauce, crème anglaise goes well with virtually every chilled soufflé.