Ultimate Croque Monsieur Recipe

Ingredients

Béchamel Sauce

• 1 ½ cups milk
• 4 tablespoons unsalted butter
• 1/4 cup flour
• 1/4 teaspoon salt
• 1/8 teaspoon ground nutmeg
• 1/8 teaspoon white pepper
• Pinch of cayenne pepper (optional)

Sandwich

• 8 slices 1/2-inch thick country-style sourdough bread or pan de mie
• 6 ounces Gruyere cheese, thinly sliced
• 6 ounces ham slices, preferably Black Forest
• 2 tablespoons Dijon mustard
• 4 tablespoons unsalted butter, divided
• 2 tablespoons olive oil, divided

Topping

• 3 ounces (¾ cup) Gruyere cheese, shredded
• 1/4 cup Parmesan cheese, grated on microplane grater

Instructions

1. Preheat the oven to 400°F and line a large baking sheet (21×15 inches) with parchment paper.
2. Melt 4 tablespoons unsalted butter in a medium-large saucepan over medium heat. Reduce heat to low; add flour and cook while whisking constantly for 2 minutes.
3. Remove from heat. Slowly whisk in about a quarter of the milk until smooth and thick. Continue adding the milk in small amounts, whisking until smooth after each addition. Add salt, nutmeg, white pepper, and cayenne pepper.
4. Return to heat and bring to a simmer, whisking continuously until béchamel thickens to a spreadable consistency like butter or pudding. Remove from heat.
5. Arrange 8 bread slices on the baking sheet. Spread half of the béchamel thickly over all slices.
6. On 4 bread slices with béchamel, layer half of the sliced Gruyere, then all the ham folded to fit, then a thick layer of Dijon mustard, and the remaining Gruyere slices. Close sandwiches with remaining bread slices, béchamel side down.
7. Heat 1 tablespoon olive oil in a cast-iron skillet over medium heat. Add 2 tablespoons butter and melt. In batches, grill sandwiches for about 2 minutes per side until deeply golden brown, pressing down occasionally.
8. Spread remaining béchamel on top slices of each sandwich. If béchamel is too thick, gently reheat and whisk with a splash of milk. Sprinkle shredded Gruyere and grated Parmesan over béchamel.
9. Bake sandwiches in the oven for 10-12 minutes until cheese melts. Then broil for 2-3 minutes until tops are golden and bubbly.
10. Serve immediately with a fork and knife to enjoy the rich, gooey cheese sandwich.

Notes

• Use authentic Gruyere for best melty, nutty flavor. Purchase sliced for layering and a block for shredding.
• Pinch of cayenne in béchamel is optional but adds a subtle kick.
• Press sandwiches firmly while pan frying to ensure even toasting and melting.
• Use a cast-iron skillet or heavy pan for best crust formation while frying.
• Serve warm immediately as the sandwich is rich, hot, and messy to handle.