The way you slice the bread is important here: cutting it into one-inch cubes is ideal to allow the chocolate milk custard to soak into it fully.
- 1 pound challah, brioche, or sweet Hawaiian bread, cut into 1 to 1 1/2 inch cubes
- 2 tablespoons light brown sugar
- 1 teaspoon ground cinnamon
- 1 1/2 teaspoons orange zest (from one small naval orange)
- 1/2 teaspoon kosher salt
- 5 large eggs
- 2 cups whole chocolate milk
- 1/2 cup heavy cream
- 1 tablespoon unsalted butter, softened
- 4 ounces (110 grams) semi-sweet chocolate, chopped (or chocolate chips), divided
1 Toast the challah: Preheat your oven to 300°F. Arrange the cubes of challah in a single layer on a half sheet pan.
Toast the bread for 15 minutes, tossing once half-way through the toasting time. Remove the pan from the oven and let the bread cool while you prepare the chocolate milk custard.
2 Mix the custard: In a large mixing bowl, combine the brown sugar, cinnamon, orange zest, salt, and eggs. Whisk the ingredients together until smooth.
Combine the chocolate milk and heavy cream and add them to the egg mixture. Whisk until the custard is no longer clumpy.
3 Assemble the casserole: Grease the ceramic insert of your slow cooker with the butter.
Add half of the bread cubes to the insert and top with a quarter of the chocolate pieces.
Add the remaining bread cubes and sprinkle on another quarter of the chocolate chunks. Reserve the rest of the chocolate for sprinkling on the finished casserole.
4 Soak the casserole: Pour all of the chocolate milk custard over the bread. Use a large spoon to toss the bread in the custard before covering with the lid and refrigerating for at least 2 or up to 24 hours.
5 Warm the ceramic insert: Before cooking the casserole, set the ceramic insert on the countertop for 30 minutes to take some of the chill off of it. This will keep it from shattering when it’s heated.
6 Cook the casserole: Place the insert into the slow cooker and cook the casserole on high for 2 1/2 hours. The internal temperature of the fully-cooked casserole should be 160-165°F
7 Cool and serve: Once the casserole is cooked, sprinkle the remaining chocolate chunks over the casserole. Cool briefly, then spoon the casserole into individual plates and serve.