For the chocolate croissant bread pudding: Preheat oven to 350 degrees F.
In a food processor, combine butter and sugar process until well blended. Add cinnamon, and vanilla, and pulse to combine.
While the processor is running crack 5 eggs into the mixture. Turn off the mixer and scrape down the sides. Add the heavy cream and pulse to combine.
Lightly butter a 9 by 13-inch baking dish. Break up the croissants into 1-inch pieces and layer in the pan. Scatter the raisins and shaved bittersweet chocolate over the top, and gently mix to incorporate. Pour the egg mixture over the croissants; soak for 8 to 10 minutes. You will need to push croissants pieces down during this time to ensure even coverage by egg mixture.
Cover with foil and bake for 35 minutes. Remove foil and bake for additional 10 minutes to brown the top. The croissant bread pudding is done when the custard is set, but still soft. Allow to cool. Serve with the Bourbon Ice Cream Sauce.
For the bourbon ice cream sauce: Place ice cream in refrigerator the day before the party.
At service, stir in bourbon and serve.