📝 About This Recipe
Born in the bustling brasseries of early 20th-century Paris, the Croque Monsieur is the sophisticated evolution of the grilled cheese sandwich. This recipe features thick slices of artisanal sourdough layered with nutty Gruyère and premium ham, all blanketed in a luxurious, nutmeg-scented Mornay sauce. It is a decadent, golden-brown masterpiece that perfectly balances crunchy textures with a rich, molten heart.
🥗 Ingredients
The Mornay Sauce
- 2 tablespoons Unsalted Butter (high quality)
- 2 tablespoons All-Purpose Flour
- 1 1/4 cups Whole Milk (warmed slightly)
- 1/2 cup Gruyère Cheese (finely grated)
- 1/8 teaspoon Nutmeg (freshly grated)
- 1 teaspoon Dijon Mustard (smooth)
- 1/4 teaspoon Kosher Salt (or to taste)
- 1 pinch White Pepper (ground)
The Sandwich Assembly
- 4 slices Sourdough or Pain de Mie (thick-cut, about 3/4 inch)
- 2 tablespoons Unsalted Butter (softened for spreading)
- 2 teaspoons Dijon Mustard (for spreading on bread)
- 4-6 slices Paris Ham or Jambon de Paris (thinly sliced, high quality)
- 1 cup Gruyère Cheese (shredded)
- 2 tablespoons Parmesan Cheese (freshly grated for the topping)
👨🍳 Instructions
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1
Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper or a silicone mat.
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2
In a small heavy-bottomed saucepan over medium heat, melt the 2 tablespoons of butter until foaming.
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3
Whisk in the flour and cook for 1-2 minutes, stirring constantly. This creates a roux; do not let it brown, it should remain a pale straw color.
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4
Slowly pour in the warm milk while whisking vigorously to prevent lumps. Continue to cook, whisking frequently, until the sauce thickens enough to coat the back of a spoon (about 4-5 minutes).
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5
Remove the saucepan from the heat. Stir in 1/2 cup of grated Gruyère, 1 teaspoon of Dijon mustard, nutmeg, salt, and white pepper. Mix until smooth and set aside.
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6
Lightly toast the bread slices in a toaster or under the broiler for 1-2 minutes per side until just barely crisp.
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7
Spread a thin layer of softened butter on one side of all four slices of bread. On two of the slices, spread a thin layer of Dijon mustard over the butter.
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8
Place the mustard-side-up slices on your prepared baking sheet. Top each with a generous spoonful of the Mornay sauce, spreading it to the edges.
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9
Layer the ham slices over the sauce, folding them to fit the bread perfectly. Sprinkle half of the remaining shredded Gruyère over the ham.
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10
Place the remaining two bread slices on top, buttered side facing up.
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11
Generously spread the remaining Mornay sauce over the top of the sandwiches, ensuring the sauce reaches the very edges of the bread to prevent burning.
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12
Sprinkle the rest of the Gruyère and the grated Parmesan over the sauce-covered tops.
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13
Bake in the center of the oven for 10-12 minutes until the cheese is melted and bubbling.
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14
Switch the oven to 'Broil' for the final 1-2 minutes, watching closely, until the tops are speckled with golden-brown, caramelized spots.
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15
Remove from the oven and let rest for 2 minutes before serving to allow the sauce to set slightly.
💡 Chef's Tips
Always use block Gruyère and grate it yourself; pre-shredded cheese is coated in potato starch and won't melt as smoothly. Don't skip the nutmeg—it is the secret ingredient that gives the Mornay sauce its authentic French character. Ensure the Mornay sauce covers the crusts of the top bread slice; this protects the bread from becoming too hard in the oven. For a 'Croque Madame' variation, simply top the finished sandwich with a sunny-side-up fried egg. If you don't have Paris ham, use a high-quality honey-roasted or smoked ham from the deli counter.
🍽️ Serving Suggestions
Serve with a simple side of butter lettuce tossed in a sharp lemon and shallot vinaigrette to cut through the richness. A few cornichons (French tart pickles) on the side provide a wonderful vinegary crunch. Pair with a crisp, dry white wine like a Sancerre or a light-bodied Pinot Noir. A chilled glass of sparkling cider is a traditional and refreshing accompaniment. For a classic bistro experience, serve with a small pile of crispy French fries (pommes frites).