Soak sultanas in hot water for 10 minutes, then drain.
Butter the bread.
Remove crusts and cut into triangles.
Arrange in a greased deep casserole dish along with raisins.
In a saucepan, bring the milk, cream, vanilla bean and sugar to just below a boil.
Remove the vanilla bean.
Add milk mixture to the eggs.
Through a strainer, pour the egg-and-milk mixture onto the bread.
Leave to soak.
Cover with aluminum foil and cook in a water bath in preheated oven, approximately 55 minutes. Remove foil and bake 5 more minutes to allow top to crisp.
To make the whiskey sauce: Boil the milk, then remove from heat.
In a separate saucepan, mix the sugar and egg yolks.
Add egg mixture to milk and return to heat.
Cook gently over low heat, stirring constantly, until sauce thickens slightly.