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A slice of blueberry French toast casserole topped with fresh berries and powdered sugar on a wooden board.

Blueberry Lemon French Toast Casserole

This delightful make-ahead casserole features sturdy challah bread soaked in a bright lemon-infused custard, layered with sweet blueberries, and baked to golden perfection. Perfect for a stress-free brunch or a special breakfast gathering.
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Prep Time 25 minutes
Cook Time 55 minutes
Total Time 1 hour 20 minutes
Servings: 8 servings
Course: Breakfast, Brunch
Cuisine: American
Calories: 450
Ingredients Equipment Method Notes

Ingredients
  

For the French Toast Casserole
  • 1 loaf challah, brioche, or day-old French bread 13-16 ounce, cut into 1-inch cubes (about 8-9 cups)
  • 8 large eggs
  • 2 cups whole milk
  • 1/2 cup heavy cream or more whole milk for a lighter casserole
  • 1/2 cup granulated sugar
  • 2 tsp vanilla extract
  • 1 tsp ground cinnamon
  • 1/2 tsp salt
  • 2 tbsp fresh lemon zest from 2-3 lemons
  • 2 tbsp fresh lemon juice
  • 2 cups fresh or frozen blueberries do not thaw if frozen
  • 2 tbsp unsalted butter melted, for greasing dish
Optional Streusel Topping
  • 1/2 cup all-purpose flour
  • 1/4 cup granulated sugar
  • 1/4 cup packed light brown sugar
  • 1/2 tsp ground cinnamon
  • 1/4 cup unsalted butter cold and cubed
Optional Lemon Glaze
  • 1 cup powdered sugar
  • 2-3 tbsp fresh lemon juice

Equipment

  • 9x13 inch baking dish
  • Large Mixing Bowl
  • Whisk
  • Zester
  • Measuring cups and spoons
  • Plastic wrap

Method
 

Prepare & Assemble the Casserole
  1. Grease a 9x13 inch baking dish generously with melted butter. Arrange the bread cubes evenly in the prepared dish.
  2. In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, cinnamon, salt, lemon zest, and lemon juice until well combined and smooth.
  3. Pour the egg custard evenly over the bread cubes in the baking dish, making sure all the bread is well saturated. Gently scatter the blueberries over the bread. Press down lightly to ensure the bread soaks up the liquid.
  4. Cover the baking dish tightly with plastic wrap and refrigerate for at least 4 hours, or preferably overnight (12-24 hours). This allows the bread to fully absorb the custard, resulting in a richer, more uniform texture.
Bake the Casserole
  1. If using the streusel topping, prepare it now: In a medium bowl, combine the flour, granulated sugar, brown sugar, and cinnamon. Cut in the cold, cubed butter using your fingertips or a pastry blender until the mixture resembles coarse crumbs.
  2. When ready to bake, preheat your oven to 375°F (190°C). Remove the casserole from the refrigerator and let it sit at room temperature for about 15-20 minutes while the oven preheats.
  3. If using the streusel topping, sprinkle it evenly over the casserole just before baking.
  4. Bake for 50-60 minutes, or until the casserole is golden brown, puffed up, and a knife inserted into the center comes out clean (no liquid egg). If the top starts to brown too quickly, you can loosely tent it with foil.
Finishing Touches & Serve
  1. Remove from oven and let stand for 10-15 minutes before serving. This allows it to set. While it rests, prepare the lemon glaze if desired: whisk powdered sugar and 2-3 tablespoons of fresh lemon juice together in a small bowl until smooth.
  2. Drizzle the glaze over individual servings or the entire casserole just before serving. Serve warm, perhaps with a dollop of whipped cream or a side of maple syrup.

Notes

For best results, use day-old bread as it absorbs the custard better without becoming soggy. You can omit the streusel and glaze for a simpler version. Leftovers can be stored in an airtight container in the refrigerator for up to 3 days. Reheat individual portions in the microwave or oven until warmed through.