Literally meaning “mister crunch,” the croque monsieur is a treasure trove of textures; pop a fried egg on top of your sandwich to transform it into a croque madame. This sandwich stars layers of thinly sliced ham, soft, melty cheese, and an audible crunch as you bite down on the toasted bread. Hidden in plain sight is a traditional Mornay sauce: a béchamel sauce that’s been upgraded with melted Gruyère. If you’re not a fan of the pungent flavors of Gruyère, feel free to opt for milder Comté.



  • 20g butter
  • 12g plain flour
  • 240ml whole milk
  • Salt
  • Freshly ground black pepper
  • 55g grated Gruyère


  • 4 slices thick country bread
  • 2 tbsp. butter, softened
  • 2 tsp. whole grain Dijon mustard
  • Mornay sauce
  • 6 slices ham
  • grated Gruyère


  • 1 tbsp. butter
  • 2 large eggs
  • salt, for sprinkling
  • Freshly ground black pepper


Step 1
Preheat oven to 350°. Make Mornay sauce: In a small saucepan over medium heat, melt butter. Add flour and stir until fragrant, 1 minute. Gradually whisk in milk and add salt, pepper, and nutmeg. Bring to a simmer, whisking constantly, and cook until sauce thickens, 2 minutes. Remove from heat and stir in Gruyère. Let cool 10 minutes.

Step 2
Assemble Croque Monsieurs: In a large ovenproof skillet over medium heat, toast bread on both sides until lightly golden. Spread half tablespoon butter on each slice, then flip over two slices and spread each with 1 teaspoon mustard and 1 tablespoon Mornay sauce. Top each mustard slice with 3 slices ham, ¼ cup Gruyère, and remaining bread slices. Evenly spread tops of each sandwich with 2 tablespoons sauce, and sprinkle with remaining Gruyère.

Step 3
Transfer skillet to oven and cook until cheese is melty and top is golden, 15 to 18 minutes.

Step 4
In a nonstick skillet over medium-high heat, melt butter. Crack eggs into skillet and fry until whites are set, 3 minutes. Season with salt and pepper and top each sandwich with an egg.

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