Overnight Croque Monsieur Casserole Recipe

Introduction

This Overnight Croque Monsieur Casserole is a rich and savory breakfast dish that combines buttery bread, tender Canadian bacon, and melted Gruyere cheese in a creamy custard. Perfect for a holiday brunch or a weekend treat, it’s easy to prepare ahead and bake fresh in the morning.

Ingredients

• 1 Tablespoon Unsalted Butter, plus more to coat pan
• 1 Yellow Onion, roughly chopped (about 1 1/2 cups)
• 4 Cloves Garlic, thinly sliced
• Salt and Pepper, to taste
• 1 Tablespoon Fresh Thyme, roughly chopped, plus 1 teaspoon for garnish
• 8 Large Eggs
• 1 1/2 Cups Half-and-Half
• 2 Tablespoons Dijon Mustard
• 1/2 Teaspoon Hot Sauce, plus more for garnish
• 1 1/2 Teaspoons Kosher Salt
• 1 Loaf Martin’s Old-Fashioned Real Butter Bread, stale or toasted, cut into thick cubes
• 2 Cups Gruyere Cheese, shredded (about 4.5 ounces)
• 1/2 Pound Canadian Bacon, cut into 1/2-inch dice
• 1/4 Cup Parmesan Cheese, finely grated (about 1 ounce)

Instructions

1. Step 1: Coat a 3-quart (13×9-inch) baking dish with butter and set aside.
2. Step 2: Place a large frying pan over medium heat and add butter. When it’s slightly frothy, add the chopped onion, season with salt, and cook until just softened, about 3 to 4 minutes. Add the sliced garlic, season with salt and pepper, and cook another minute until fragrant. Remove from heat and stir in the chopped thyme.
3. Step 3: In a large bowl, whisk together eggs, half-and-half, Dijon mustard, hot sauce, and kosher salt until evenly combined. Arrange half of the bread cubes in the bottom of the prepared dish. Sprinkle with 1 cup of Gruyere cheese, half of the onion-garlic mixture, and half of the Canadian bacon. Repeat layering with the remaining bread, onion mixture, bacon, and Gruyere.
4. Step 4: Pour the egg custard evenly over the layers. Press down gently on the bread to fully submerge it. Cover the dish tightly with plastic wrap, place a heavy plate or weight on top, and refrigerate for 3 to 12 hours.
5. Step 5: When ready to bake, remove the weight and plastic wrap. Cover the casserole with aluminum foil and place on the middle rack of the oven. Set the oven to 325°F (do not preheat) and bake for 35 minutes. Then remove the foil, sprinkle the Parmesan cheese over the top, and increase the temperature to 375°F. Bake an additional 10 to 15 minutes until golden and bubbly.
6. Step 6: Remove from oven, sprinkle the remaining thyme on top, and let cool for at least 5 minutes before serving. Offer extra hot sauce on the side for added zing.

Tips & Variations

• Use day-old or lightly toasted bread to prevent the casserole from becoming too soggy.
• Substitute ham for Canadian bacon if preferred.
• Fresh herbs like tarragon or parsley work well in place of thyme for a different flavor.
• Add sautéed mushrooms or spinach to the onion mixture for extra veggies.
• For a richer custard, use heavy cream instead of half-and-half.

Storage

Store leftover casserole covered in the refrigerator for up to 3 days. Reheat individual portions in the microwave or warm slices in a 350°F oven until heated through. This casserole can also be frozen for up to 2 months; thaw overnight in the refrigerator before reheating.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I prepare this casserole without refrigerating overnight?

Yes, after assembling, you can bake it immediately, but refrigerating for several hours enhances the custard’s flavor and texture by allowing the bread to soak it evenly.

What can I use if I don’t have Gruyere cheese?

Swiss cheese or Emmental are great substitutes that melt well and offer similar nutty flavors. Avoid very mild cheeses as they won’t provide the distinctive taste of a Croque Monsieur.

Overnight Croque Monsieur Casserole Recipe

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★★★★★

4.6 from 111 reviews

This Overnight Croque Monsieur Casserole is a decadent and comforting brunch dish featuring layers of buttery bread, savory Canadian bacon, caramelized onions, and Gruyere cheese all soaked in a flavorful egg custard. Prepared the night before and baked in the morning, it yields a golden, cheesy strata perfect for serving a crowd.

• Author: Dylan
• Prep Time: 15 minutes
• Cook Time: 50 minutes
• Total Time: 3 hours 15 minutes to 12 hours 50 minutes (including soaking time)
• Yield: Serves 12 1x
• Category: Breakfast, Brunch, Casserole
• Method: Baking
• Cuisine: French

Ingredients

Scale 1x2x3x

For the Onion-Garlic Mixture

• 1 Tablespoon Unsalted Butter, plus more to coat pan
• 1 Yellow Onion, roughly chopped (about 1 1/2 cups)
• 4 Cloves Garlic, thinly sliced
• Salt and Pepper, to taste
• 1 Tablespoon Fresh Thyme, roughly chopped, plus 1 teaspoon for garnish

For the Custard and Casserole

• 8 Large Eggs
• 1 1/2 Cups Half-and-Half
• 2 Tablespoons Dijon Mustard
• 1/2 Teaspoon Hot Sauce, plus more for garnish
• 1 1/2 Teaspoons Kosher Salt
• 1 Loaf Martin’s Old-Fashioned Real Butter Bread, stale or toasted, cut into thick cubes
• 2 Cups Gruyere Cheese, shredded (about 4.5 ounces)
• 1/2 Pound Canadian Bacon, cut into 1/2-inch dice
• 1/4 Cup Parmesan Cheese, finely grated (about 1 ounce)

Instructions

1. Prepare the Baking Dish: Coat a 3-quart (13×9-inch) baking dish with butter and set it aside to prevent sticking during baking.
2. Cook Onion and Garlic: Heat a large frying pan over medium heat and melt the butter. When it becomes slightly frothy, add the chopped onion and season with salt. Cook for about 3 to 4 minutes until softened. Then add garlic, season with salt and pepper, and cook for about 1 minute until fragrant. Remove from heat and stir in the chopped fresh thyme.
3. Mix Custard: In a large bowl, whisk together the eggs, half-and-half, Dijon mustard, hot sauce, and kosher salt until well combined to create the custard base.
4. Assemble Casserole: Arrange half of the cubed bread in the bottom of the prepared baking dish. Sprinkle 1 cup of shredded Gruyere cheese evenly over the bread, then add half of the onion-garlic mixture and half of the diced Canadian bacon. Repeat the layers with the remaining bread, onion mixture, ham, and Gruyere cheese. Pour the egg custard evenly over the assembled ingredients.
5. Soak Overnight: Press the bread down gently to fully submerge it in the custard. Cover the dish tightly with plastic wrap and place a heavy plate or weight on top. Refrigerate the casserole for 3 to 12 hours to allow the bread to absorb the custard flavors.
6. Bake Covered: When ready to cook, remove the weight and plastic wrap. Cover the casserole with aluminum foil and place it on the middle rack of the oven. Set the oven temperature to 325°F (no preheating needed) and bake for 35 minutes.
7. Finish Baking Uncovered: Remove the foil and sprinkle the finely grated Parmesan cheese evenly over the top of the casserole. Increase the oven temperature to 375°F and bake uncovered for an additional 10 to 15 minutes until the top is golden brown and bubbly.
8. Rest and Serve: Remove the casserole from the oven and sprinkle the remaining fresh thyme over the top. Allow it to cool for at least 5 minutes before slicing. Serve warm with hot sauce on the side if desired.

Notes

• Stale or toasted bread works best to absorb the custard without becoming too mushy.
• Using Martin’s Old-Fashioned Real Butter Bread will add richness and authenticity to the dish.
• You can prepare this casserole up to 12 hours in advance, making it ideal for easy entertaining.
• Feel free to substitute Canadian bacon with ham or cooked bacon depending on preference.
• Adjust hot sauce quantity based on your preferred spice level.
• Make sure to press the bread down firmly so it soaks evenly in the egg custard.
• Allowing the casserole to rest after baking helps it set and makes slicing easier.

Keywords: Croque Monsieur, breakfast casserole, overnight casserole, brunch recipe, French strata, Gruyere cheese, Canadian bacon, egg custard