Can I use frozen blueberries in a blueberry french toast casserole?

Yes, and in December they are often the better berry. Use them straight from the freezer, never thawed, and toss them in a teaspoon of flour first. Thawed berries leak juice into the custard all night and turn the crumb gray; frozen ones burst in the oven instead.

How far ahead can I assemble it, 24 or 48 hours?

Twenty four hours is the sweet spot: the bread drinks fully and the eggs stay fresh in flavor. At 48 hours the custard can start to taste tired and the crumb oversoftens. For anything longer, freeze the assembled pan and thaw it overnight instead.

My bread is fresh from the bakery. Do I really need to dry it?

Yes, ten minutes is enough. Cubes dried at 300°F for 10 minutes lose the surface moisture that makes fresh bread collapse into pudding. Day-old bread skips the step entirely, which is why the recipe is written around it.

Does it bake the same in a glass dish as in a metal pan?

Nearly. Glass holds heat longer, so pull the casserole when the center is just set; it keeps cooking as it rests. Metal gives slightly crisper edges. Both work at 350°F, and the foil covered first stage matters more than the material.

How do I reheat one square so it tastes fresh baked?

Use a skillet, not the microwave. Warm the square cut side down in a little butter over medium heat for 2 to 3 minutes per side. The base crisps, the custard warms through, and the streusel stays a lid instead of going soft.

Blueberry French Toast Casserole For A Slow Christmas Morning

Ingredients

Scale

1 loaf (about 1 pound) day-old brioche or challah, cut into 1 inch cubes (about 10 cups)
8 ounces cream cheese, cut into small cubes
2 cups blueberries, fresh or frozen (toss frozen berries with 1 teaspoon flour)
8 large eggs
1 1/2 cups whole milk
1/2 cup heavy cream
1/3 cup granulated sugar
1/4 cup maple syrup, plus more to serve
2 teaspoons vanilla extract
1 teaspoon ground cinnamon
1 teaspoon lemon zest
1/4 teaspoon fine salt
1/3 cup packed light brown sugar (streusel)
1/3 cup all-purpose flour (streusel)
1/2 teaspoon ground cinnamon (streusel)
6 tablespoons cold unsalted butter, cubed (streusel)
1 1/2 cups blueberries (sauce)
2 tablespoons granulated sugar (sauce)
1 teaspoon cornstarch (sauce)
1/4 cup water (sauce)
1 teaspoon lemon juice (sauce)
Confectioners’ sugar, to serve

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Instructions

If the bread is fresh, dry the cubes on a sheet pan in a 300°F oven for 10 minutes and cool them. Butter a 9×13 inch baking dish.
Spread half the bread cubes in the dish. Scatter the cream cheese cubes and half the blueberries over them, then cover with the remaining bread and the rest of the blueberries.
Whisk the eggs, milk, cream, granulated sugar, maple syrup, vanilla, cinnamon, lemon zest and salt. Pour slowly over the bread, pressing the top cubes down gently so every piece drinks.
Cover the dish and refrigerate for at least 8 hours, up to 24 hours. The casserole goes in on Christmas Eve and waits for morning.
Make the streusel, the same night or just before baking. Rub the brown sugar, flour and cinnamon with the cold butter until coarse crumbs form. Keep it covered in the fridge.
On Christmas morning, set the dish on the counter for 30 minutes. Heat the oven to 350°F. Scatter the streusel evenly over the top.
Bake covered with foil for 30 minutes, then uncovered for 20 to 25 minutes, until puffed, deep golden and set at the center, 160°F inside, with no liquid egg when a knife goes in.
While it bakes, make the sauce. Simmer the sauce blueberries, sugar, cornstarch and water for 5 to 6 minutes, until the berries burst and the sauce turns glossy. Stir in the lemon juice.
Rest the casserole 10 minutes. Dust with confectioners’ sugar, cut into squares and serve with the warm blueberry sauce spooned over.

Author: Chef Rita
Prep Time: 20 minutes, plus at least 8 hours chilling
Cook Time: 55 minutes

Nutrition

Serving Size: 1
Calories: 500
Sugar: 26
Sodium: 300
Fat: 28
Saturated Fat: 15
Unsaturated Fat: 13
Trans Fat: 0
Carbohydrates: 52
Fiber: 2
Protein: 11
Cholesterol: 215