Preheat oven to 325 degrees F. Adjust oven rack to center position. Lightly butter eight small (1/4 cup) custard cups or ramekins and set them into a large baking dish.
In a large bowl, beat egg and egg yolks slightly; add salt and white truffle oil. Mix in hot cream until blended. Pour egg mixture into prepared custard cups; place baking dish with custard cups into hot oven. Carefully pour warm water into the baking pan to come half-way up the sides of the custard cups.
Bake 15 to 20 minutes or until a knife inserted near the center comes out clean. Remove from oven and immediately remove cups from water bath.
While the custard is baking, reduce the beef stock until it is syrupy. Add cabernet wine and stir to combine.
To serve, place warm custards on individual serving plates. Top with truffle shavings and 1 to 2 teaspoons warm beef/cabernet sauce.
You always want to maximize the truffle flavor, using the least amount of the ingredient as possible. So always slice into paper-thin wedges or strips. Use a truffle shaver (similar to a cheese grater) when shaving truffles. Learn about Oregon Black Truffles.
May be served warm or at room temperature.
Makes 8 to 10 servings (depending on size of custard cups).
Truffle Custard Recipe https://whatscookingamerica.net/custardtruffle.htm