• Dry out the croissants. Tear or cut the croissants into pieces and lay them out on a baking sheet uncovered overnight. If you're short on time, pop the tray into a 200ºF oven for 30 minutes. Let the croissants cool before using.
• Layer the casserole. Lightly grease a 9x13-inch or 3 qt baking dish with nonstick spray or butter. Arrange half of the croissant pieces in the dish and top with the diced cream cheese, dollops of blueberry preserves, and half of the fresh blueberries. Top with the remaining croissant pieces and fresh blueberries.
• Make the custard. Combine the sugar and lemon zest in a mixing bowl and use your fingers to mix the zest into the sugar until very fragrant. Then, whisk in the half and half, eggs, vanilla, salt, and optional Grand Marnier until very smooth.
• Soak the casserole. Pour the custard mixture all over the casserole and press down gently to submerge the croissants and filling. Cover with foil and transfer to the refrigerator for at least 1 hour, up to 12 hours.
• Preheat an oven to 350ºF.
• Bake. Transfer to the oven and bake covered for 20 minutes. Uncover and bake for 30 minutes more, until the tops of the croissants are golden brown and the custard is set and not runny.
• Serve. Remove from the oven and cool for 30-40 minutes before serving. Top with a dusting of powdered sugar and serve with whipped cream.

Storage Instructions

• To store: Leftovers should be tightly covered and stored in the refrigerator for up to 4 days. 

  To reheat: Reheat individual servings in the microwave for 1 minute, then in additional 30-second intervals as needed. I actually prefer reheating this casserole in a 325ºF oven (covered with foil) for about 20 minutes; the texture is better preserved this way.

  To freeze: Make recipe as instructed. Cool completely after baking, then tightly wrap in plastic wrap and foil. Freeze for up to 2 months. When ready to cook, thaw casserole in the refrigerator overnight before baking for 20 minutes at 325ºF.