Start by preparing the béchamel sauce.
In a saucepan with high sides, melt the butter.
Once the butter has melted, add the flour and start whisking.
As soon as the mixture starts to change color slightly, add the milk and continue whisking.
When the whisk starts to meet resistance, add the salt and a pinch of nutmeg.
Set the béchamel sauce aside and let it cool.
Cut two slices of sandwich bread, about an inch thick.
Spread the béchamel sauce on both slices of bread.
Add 3 to 4 slices of ham on one slice and a generous amount of grated Emmental or Gruyère cheese, then close the croque monsieur.
Heat a non-stick skillet over medium heat.
Start toasting the croque monsieur. To help the cheese melt, cover the skillet with a lid or place the pan in the oven for a few minutes.
Serve hot, crispy, and cheesy.Enjoy your meal!