Remove crusts from brioche. Cut into cubes and dip in butter. Put on baking sheet and toast in oven. Arrange bread in a buttered 2- to 2 1/2-inch deep pan (12 or 13 inches square).
Bring milk and cream to a boil; remove from heat. Add a little of the hot mixture to yolks to bring up the temperature. Whisk yolks and sugar into milk mixture. Melt chocolate. Stir chocolate into custard. Stir in vanilla extract. Pour over bread. Work custard into bread. Let stand for 1 hour.
Heat oven to 325° F. Put pan in a larger pan with hot water coming halfway up sides to make a water bath. Bake 1 hour.
To make sauce, melt white chocolate in double boiler. Remove from heat source. Let cool at room temperature. Using a wooden spoon, gently fold in whipped cream. Stir in brandy or liqueur of choice. Refrigerate. Serve cold over bread pudding.
Makes about 1/2 cup.Makes 12 Source: