Classic croque-monsieur with béchamel

Ingredients

For the béchamel

• 20 g unsalted butter

• 20 g of wheat flour

• 200 ml of whole milk

• 1 pinch of freshly grated nutmeg

• 1/4 teaspoon salt, or to taste

• Black pepper or ground white pepper, to taste

For croques

• 8 slices of firm white bread or pain de mie, about 1 cm thick

• 20 g of ointment butter

• 20 g Dijon mustard, about 1 teaspoon per sandwich

• 240 g thinly sliced cooked ham, about 60 g per sandwich

• 200 g of grated Gruyère, divided between filling and topping

Preparation method

1. Heat the oven and prepare the bread

Preheat the oven to 210°C, with a rack in the upper half. Spread a very thin layer of butter on the outer sides of the 8 slices. Place them on a baking tray, buttered side up, and bake for 3 to 4 minutes, just until the surface loses moisture and starts to set. Don't let it brown too much at this stage.

2. Make the béchamel roux

Melt the 20 g of butter in a small pan over low to medium heat. Add the flour and stir with a whisk for about 2 minutes, until a smooth, foamy paste forms, still light. The goal is to cook out the raw taste of the flour without darkening the roux.

3. Thicken the béchamel

Add the milk little by little, in 4 or 5 additions, stirring well each time to keep the sauce smooth. When all the milk is incorporated, cook over medium-low heat for 3 to 5 minutes, stirring, until the sauce is thick and spreadable. Season with nutmeg, salt and pepper. Set aside off the heat.

4. Assemble the filling

Place 4 slices of bread on the baking sheet, with the pre-toasted and buttered side facing down. Spread about 5 g of Dijon over each slice. Distribute 30 g of Gruyère, 60 g of ham and around 15 g of béchamel on each base. Cover with the other 4 slices, leaving the pre-toasted side facing up, and press lightly just to stabilize.

5. Cover without soaking

Spread about 40 g of béchamel over the top of each sandwich, getting close to the edges without letting the sauce run down the sides. Finish each with 20 g of the remaining Gruyère. The topping should form a continuous layer, but not so thick that it sinks into the bread.

6. Bake and brown

Bake in the oven at 210°C for 8 to 10 minutes, until the cheese in the filling melts and the center is very hot. Then, activate the grill and grill for 1 to 3 minutes, watching without moving away, until the surface bubbles and gains golden spots. If the oven does not have a grill, increase it to 230°C and leave it on the highest rack for another 2 to 4 minutes.

7. Rest and serve

Remove from the oven and wait 2 minutes before cutting. This brief rest firms the béchamel and reduces the chance of the filling oozing out all at once. Serve while still hot.

Right spot / how to know it’s ready

The croque-monsieur is done when the edges of the bread are firm and crispy, the cheese filling is completely melted and the topping has bubbles with golden to brown spots. The béchamel should remain creamy and thick on the bread, without forming a liquid pool in the pan. When cutting, the center must be hot and the base bread must still support the filling.

Tips for the recipe to work out

Use firm bread, not overly fresh

Very soft, moist bread absorbs the sauce before creating structure. Short pre-roasting dries the surface and helps maintain the contrast between soft crumb and crispy edges.

Paint the béchamel into a spreadable texture

For this recipe, the sauce needs to be thicker than pasta sauce. When you pass the spatula along the bottom of the pan, it should open a path that takes a moment to close. If it is fluid, cook for another 1 or 2 minutes before assembling.

Grate the cheese finely

Finely grated cheese melts more quickly and evenly, which reduces the time needed to heat the sandwich and reduces the risk of burning the bread before the center is hot.

Gratine only at the end

The grill is used to color the surface, not to cook the sandwich from cold. First heat and melt the filling in the oven; Only then bring the cover closer to the intense heat.

Substitutions and variations

Gruyère delivers a buttery and slightly almond flavor. Emmental can replace it for a smoother and more elastic result; Comté works well when a more pronounced flavor is desired. It is also possible to mix two of these cheeses, keeping the total to 200 g.

If you can't find pain de mie, use white sliced bread with good structure, preferably with not too thin slices. Breads that are too sweet or extremely fluffy tend to lose texture contrast.

with the béchamel.

To make croque-madame, prepare the croque-monsieur in exactly the same way and, after browning, place a fried egg on each unit. The egg is the variation; You don't need to go through the croque-monsieur assembly.

How to store

The best result is obtained immediately after browning. If there are leftovers, refrigerate in an airtight container within 2 hours and consume within 3 to 4 days. To reheat, prefer oven or air fryer to recover some of the crispiness and heat the center to 74 °C. Freezing the finished sandwich is not recommended for quality, because the béchamel can lose homogeneity and the bread tends to be more humid after thawing.

How to serve / side dishes

Serve with a green salad made from bitter or slightly acidic leaves, which balances the richness of the cheese and béchamel. For brunch or a light lunch, a simple salad with Dijon vinaigrette works without competing with the sandwich.

Common mistakes

Why was my croque-monsieur soggy?

The most common causes are too liquid béchamel, too moist bread or too much sauce between the slices. Thicken the béchamel until it is spreadable, pre-toast it and keep most of the sauce in the topping, where it can brown instead of penetrating the crumb.

Why did the top burn before the cheese inside melted?

This happens when the grill goes in too early or the pan is too close to the heating element from the start. Heat the sandwich first to 210°C and only use the grill for the final few minutes.

Why does my béchamel have lumps?

Typically the milk was added too quickly or the roux was not mixed evenly. Add the milk in small portions and stir until the mixture is smooth before the next addition. If there are still small lumps, strain the sauce through a sieve before assembling.