4 C. whole milk
1-1/2 C. sugar, plus more for sprinkling
12-oz can frozen orange juice concentrate
3/4 C, plus 2 T. bourbon
2 large eggs
6 egg yolks
12 C. day-old challah, cubed
4 T. unsalted butter
3/4 C. bittersweet chocolate chunks
pinch of salt
3/4 C heavy cream
1. Heat the milk, 1 C sugar and 1/2 C orange juice concentrate in a saucepan over med-low heat until the sugar dissolves, stirring. Cool slightly. It's OK if the mixture curdles slightly.
2. Whisk the milk mixture, 2 T bourbon and the whole eggs and yolks in a large bow; fold in the bread. Cover and refrigerate until the liquid is absorbed, about 1-1/2 hours.
3. Preheat the oven to 350. Butter a 9x13 baking dish. Fold the chocolate chunks into the bread mixture. Spread evenly in the baking dish and sprinkle with sugar. Bake until a knife inserted into the center comes out clean, about 1 hour 20 minutes.
4. Meanwhile, make the sauce. Melt 4 T, butter in a small saucepan over medium heat. Add the remaining 1/2 C. sugar and cook, stirring, until lightly caramelized, 5-6 minutes. Whisk in the remaining 1 C. orange juice concentrate, 3/4 C. bourbon and the salt. Cook until thick, 10-15 minutes. Stir in the cream and simmer until the sauce coats a spoon, about 10 minutes more. Slice the bread pudding and drizzle with the sauce.