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Overnight Blueberry French Toast Casserole - A Make-Ahead Breakfast Favorite

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Prep Time 15 minutes
Cook Time 45 minutes
Total Time 1 hour
Servings: 8 servings
Ingredients Method

Ingredients
  

  • 1 loaf (14 to 16 ounces) day-old brioche or challah, cut into 1-inch cubes
  • 2 cups fresh or frozen blueberries (no need to thaw if frozen)
  • 8 large eggs
  • 2 1/2 cups whole milk or 1 1/2 cups milk + 1 cup half-and-half for extra richness
  • 1/2 cup granulated sugar
  • 1/4 cup brown sugar, packed
  • 2 teaspoons pure vanilla extract
  • 1 teaspoon ground cinnamon
  • 1/4 teaspoon ground nutmeg (optional)
  • 1/2 teaspoon fine sea salt
  • 2 tablespoons unsalted butter, melted, plus more for greasing the dish
  • 2 tablespoons turbinado sugar (optional, for a crisp top)
  • Maple syrup, for serving
  • Powdered sugar, for serving
  • Lemon zest from 1 lemon (optional, brightens the blueberry flavor)

Method
 

  1. Prep the dish: Grease a 9x13 inch baking dish with butter. Set aside.
  2. Cube the bread: Cut the brioche or challah into 1-inch cubes. If the bread is very fresh, spread the cubes on a sheet pan and let them sit out for 30 to 60 minutes to dry a bit.
  3. Layer the casserole: Add half the bread cubes to the dish. Scatter half the blueberries over the bread. Top with the remaining bread and then the remaining blueberries.
  4. Make the custard: In a large bowl, whisk together eggs, milk, granulated sugar, brown sugar, vanilla, cinnamon, nutmeg, salt, melted butter, and lemon zest if using. Whisk until smooth and well combined.
  5. Soak the bread: Pour the custard evenly over the bread and berries, pressing gently with the back of a spatula so the top layer starts to absorb the liquid. Cover tightly with foil or wrap.
  6. Chill overnight: Refrigerate for at least 6 hours and up to 18 hours. The longer soak helps the center become custardy and tender.
  7. Preheat and prep: In the morning, take the dish out of the fridge while you preheat the oven to 350°F. Let the casserole sit at room temperature for 20 minutes to remove the chill.
  8. Add a crunchy top: If you like a crisp finish, sprinkle turbinado sugar evenly over the surface.
  9. Bake: Cover with foil and bake for 25 minutes. Remove the foil and bake another 20 to 25 minutes, until the top is golden and the center is set with only a slight jiggle. An instant-read thermometer in the center should read about 175°F to 185°F.
  10. Rest and serve: Let it rest for 10 minutes. Dust with powdered sugar, slice into squares, and serve with warm maple syrup.