Bechamel sauce :

• For me, it remains an essential ingredient for an ultra-soft croque monsieur, creamy and tasty.
• Prepare the white roux: Melt the butter in a saucepan and, off the heat, pour in the sifted flour. Use a whisk, preferably silicone, to avoid scratching the pan. Mix well to smooth the breadcrumbs.
• Dilute with milk: Always, off the heat, add a little cold milk and whisk to dilute. Add a little more milk and whisk to smooth and liquefy.
• Thicken: Stir in remaining milk and return to medium heat to thicken. The mixture should be smooth and lump-free. If not, strain the mixture through a sieve.
• Whisk continuously to prevent the béchamel sauce from sticking to the bottom of the pan and burning.

Preparing the bechamel sauce

• It will gradually thicken. Season with salt, pepper and a pinch of nutmeg. When it starts to bubble, it will have thickened considerably.

  Remove from heat when smooth and creamy. It will thicken further as it cools.
• Set aside to cool, stirring occasionally. You can film it on contact and refrigerate until ready to use.

Assemble the sandwiches:

• Melt a little butter and leave to cool.
• Line a baking sheet with parchment paper and place the slices of bread on top. If you are going to pan-fry them, use a clean work surface.
• Using a pastry brush, lightly coat the top of each slice of sandwich bread with melted butter.
• Spread generously with bechamel sauce. Let the cheese overflow a little for a slobbery look after cooking. If you don't like it, spread the bechamel without overflowing.
• Place a slice of cheese on top, or a slice and a half to cover the entire surface.
• Place one or 2 slices of ham on top. You can add a 2nd slice of cheese on top of the ham if you wish. Close each sandwich with a slice of sandwich bread.
• Coat with melted butter.

Croque monsieur assembly

Pan-frying :

• or in a croque monsieur maker
• In a non-stick frying pan, melt a little butter over medium heat.
• Brown the croque-monsieur on both sides until golden brown and the cheese has melted.
• Serve immediately.
• For cooking in the maker, follow the manufacturer's instructions.

Oven cooking :

• For a more gratiné version
• Preheat the oven to 210°C (410°F).
• Spread bechamel sauce over the top of each croque monsieur and sprinkle with cheese, in this case Gruyère.
• Place in the oven for 15-20 minutes, until the cheese has melted and the bread is golden brown.
• You can then put them on the grill for 3 to 4 minutes to brown the cheese.

Serve and enjoy :

• Serve immediately with a few salad leaves drizzled with vinaigrette and fries if you want to enjoy your croque monsieur like in a traditional bistro.
• You can use a fork and knife or enjoy it by hand. It's up to you.