Equipment
* optional
Ingredients
Bechamel Sauce
- 20 g unsalted butter
- 20 g all-purpose flour
- 200 ml whole milk, cold
- 2 g kosher salt
- 1 g black pepper, freshly cracked
- 1 g ground nutmeg, freshly grated preferred
Sandwich Assembly
- 4 pain de mie, thick slices
- 20 g unsalted butter, softened
- 15 g dijon mustard
- 4 ham, thinly sliced
- 120 g gruyere cheese, freshly grated
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 837 kcal
- Protein
- 34 g
- Carbohydrates
- 63 g
- Fat
- 50 g
- Fiber
- 3 g
- Sugar
- 10 g
- Sodium
- 1914 mg
- Saturated Fat
- 27 g
- Monounsaturated Fat
- 16 g
- Polyunsaturated Fat
- 5 g
- Cholesterol
- 138 mg
- Potassium
- 396 mg
- Calcium
- 833 mg
- Iron
- 3.4 mg
- Magnesium
- 65 mg
- Phosphorus
- 615 mg
- Zinc
- 4.0 mg
- Vitamin A
- 346 mcg
- Vitamin C
- 0 mg
- Vitamin D
- 2.0 mcg
- Vitamin E
- 1.8 mg
- Vitamin K
- 7 mcg
- Vitamin B6
- 0.2 mg
- Vitamin B12
- 1.8 mcg
- Thiamin
- 0.66 mg
- Riboflavin
- 0.69 mg
- Niacin
- 4.5 mg
- Folate
- 99 mcg
- Water
- 174 g
Sources: USDA FoodData Central
Method
Preheat the oven to 200°C or 400°F and line a baking sheet with parchment paper.
In a small saucepan over medium heat, melt 20 grams of butter for the bechamel sauce.
Add the all-purpose flour to the melted butter and whisk constantly for 2 minutes to cook out the raw flour taste, creating a pale, bubbling roux.
Gradually pour the cold whole milk into the saucepan in a thin, steady stream while whisking vigorously to prevent lumps from forming.
Bring the mixture to a gentle simmer and continue whisking for 3 to 4 minutes until the sauce thickens significantly.
Remove the saucepan from the heat and stir in the salt, black pepper, and ground nutmeg. Set the bechamel aside to cool slightly.
Place the slices of pain de mie on a clean work surface and spread a thin layer of Dijon mustard evenly over one side of two of the slices.
Layer two slices of ham over each mustard coated slice of bread.
Distribute exactly half of the freshly grated Gruyere cheese evenly over the ham layers.
Place the remaining two slices of bread on top to close the sandwiches, then spread the softened butter evenly on the top exterior of each sandwich.
Heat a skillet over medium heat. Place the sandwiches butter side down into the skillet, then butter the tops. Toast for 2 minutes per side until lightly golden brown, then transfer to the prepared baking sheet.
Spoon the prepared warm bechamel sauce generously over the top of each toasted sandwich, spreading it to the edges so it slightly drips down the sides.
Sprinkle the remaining grated Gruyere cheese evenly over the bechamel layer on both sandwiches.
Bake in the preheated oven at 200°C or 400°F for 5 minutes, then switch the oven to the broil setting for an additional 2 to 3 minutes until the cheese is bubbling and deeply browned in spots. Ensure the internal temperature of the ham reaches 74°C or 165°F.
Remove the sandwiches from the oven and let them rest on the baking sheet for 3 minutes before serving to allow the molten cheese and sauce to set slightly.
Chef's Notes
- For the smoothest bechamel, ensure your milk is cold when adding it to the hot roux. The temperature contrast prevents the starch from gelatinizing too rapidly and forming lumps.
- Toasting the bread lightly in a skillet before adding the heavy sauce creates a crisp barrier that stops the bechamel and mustard from turning the crumb soggy in the oven.
- Traditional Croque Monsieur uses Jambon de Paris, but any high-quality, thinly sliced ham that is not overly sweet or smoked will work perfectly.
- Grate your own Gruyere from a block rather than buying pre-shredded cheese. Pre-shredded cheese contains anti-caking agents like cellulose that prevent smooth melting.
Storage
Refrigerator: 3 days — Store in an airtight container. Bread will soften significantly.
Reheating: Reheat in a 180C or 350F oven for 10 to 12 minutes until heated through and crisp.
Troubleshooting
Bechamel sauce is lumpy
Cause: Cold milk was added too quickly or whisking was insufficient while incorporating the liquid
Fix: Vigorously whisk the sauce or pour it through a fine-mesh strainer before adding it to the sandwich
Prevention: Add milk in a very slow, steady stream while whisking vigorously without stopping
Bottom of sandwich is soggy
Cause: Oven temperature was too low or sandwich was not toasted prior to baking
Fix: Cannot be fixed once assembled and baked
Prevention: Always pan-toast the bread lightly before assembling and baking with the wet sauce
Cultural Context
The Croque Monsieur first appeared on the menus of Parisian cafes in 1910. Its name translates playfully to bite mister, reflecting its humble origins as a quick, substantial hot lunch for urban workers. Over time, it has evolved from a simple toasted ham and cheese sandwich into a global culinary icon, celebrated for its indulgent combination of rich bechamel and perfectly melted Gruyere.
