Croque-Monsieur Breakfast Casserole

A comforting, indulgent breakfast casserole inspired by the classic French Croque-Monsieur, featuring layers of buttery bread, savory ham, and melted Gruyère and Parmesan cheeses, baked in a creamy custard base. Perfect for brunch gatherings or weekend indulgence, with customizable options for dietary preferences.

Basic Information

• Prep Time: 30 minutes (including bread slicing and custard preparation)

• Chilling Time: 30 minutes (minimum) to overnight (recommended for optimal flavor)

• Cook Time: 40–45 minutes

• Total Time: 1 hour 40 minutes to 2 hours (including chilling)

• Servings: 6–8

• Difficulty: Easy

Ingredients (for 6–8 servings)

• 4 tablespoons unsalted butter, softened (plus extra for greasing the pan)

• 1 (10–12 ounce) day-old or stale baguette, sliced into ½-inch thick pieces (about 8–10 slices)

• 3 tablespoons Dijon mustard

• 6 ounces thin-sliced French-style deli ham (e.g., Jambon de Paris or prosciutto)

• 1½ cups whole milk

• 1½ cups half-and-half or heavy cream (heavy cream for richer texture)

• 4 large eggs

• 2 egg yolks

• Freshly ground black pepper (to taste)

• 3 ounces Gruyère cheese, shredded (about 1 cup)

• 1 ounce finely grated Parmesan cheese (packed, about ¼ cup)

• Fresh parsley leaves, torn (for garnish)

• Yellow mustard and cornichons (for serving, optional)

Preparation Steps

Step 1: Preheat Oven and Assemble the Base

1. Preheat oven to 325°F (165°C). Generously butter a 9×13-inch (or 1.5–2-quart) baking dish. For a snug fit, use an 8×8-inch square dish (see Recipe Notes for pan adjustments).

2. Butter one side of each baguette slice. On the opposite side, spread a thin, even layer of Dijon mustard (avoid excess to prevent overpowering).

3. Arrange the buttered bread slices in the dish, shingled (overlapping slightly) to cover the pan without gaps. Drape ham slices evenly over the bread, allowing some bread to peek through.

Step 2: Prepare and Pour the Custard

1. In a large bowl, whisk together milk, half-and-half (or heavy cream), eggs, egg yolks, and black pepper until smooth.

2. Slowly pour the custard over the bread and ham, ensuring all bread is submerged. Let sit 5 minutes to distribute liquid.

3. Sprinkle shredded Gruyère and Parmesan over the top, leaving small gaps where ham is visible.

Step 3: Chill and Bake

1. Cover the dish tightly with plastic wrap (or foil) and refrigerate for 30 minutes minimum (or up to 24 hours).

2. Remove from fridge, let rest at room temperature 15 minutes, then bake 40–45 minutes until custard is set (toothpick test: clean or with moist crumbs).

3. Rest 20 minutes before garnishing with parsley.

Serving & Notes

• Serve: Warm or at room temperature, with mustard and cornichons. Leftovers reheat well in a 350°F oven for 15–20 minutes.

• Recipe Notes:

• Pan Size: 8×8-inch pan works better (no overflow).

• Bread: Stale day-old bread prevents sogginess.

• Vegetarian: Replace ham with sautéed mushrooms/shallots in butter.

Reader Reviews

• "Leftovers are delicious! Use 8×8 pan to avoid gaps."

• "Tastes like a Croque-Monsieur—great for potlucks."

• "Replace ham with mushrooms for a vegetarian swap; reheats beautifully."

• "Butter on bread adds excess fat—opt for classic sandwich instead."

Adapted for clarity and professionalism while preserving the original recipe integrity.