How to Make It
Preheat the oven to 350°. Butter a shallow, 2-quart baking dish and spread the torn brioche in it. Scoop the ice cream into a glass bowl and warm in the microwave in 20-second bursts, stirring, just until melted. Whisk in the eggs, sugar and 3/4 cup of water. Pour the custard over the brioche and let stand for 15 minutes, pressing to submerge the bread in the custard.
Bake the bread pudding for 30 to 35 minutes, until the top is browned. Let cool slightly.
In a medium saucepan, combine the sugar with 2 tablespoons of water. Cook over moderate heat, swirling the pan and brushing down the side with a wet pastry brush, until the sugar dissolves. Cook undisturbed until a medium-amber caramel forms, about 5 minutes. Add the cream (be careful, it may boil vigorously) and simmer, whisking, until the caramel is smooth, 1 to 2 minutes. Let cool slightly, then stir in the whiskey and salt.
Serve the warm bread pudding with the caramel sauce.