Béchamel: Save on prep time by making the white sauce ahead of time.
Croque Madame: To make this into a Croque Madame sandwich, make the recipe as instructed, then fry eggs (one for each sandwich, sunny-side up) in a separate skillet while the sandwiches toast in the oven. Place an egg on top each sandwiches.
¼ cup unsalted butter (½ stick)
¼ cup all-purpose flour
1½ cups whole milk
salt and freshly ground black pepper
1 teaspoon Dijon mustard
dash of ground nutmeg
8 thin slices white sandwich breads
5 ounces good quality ham about 8 slices
6 ounces Gruyere cheese ,or Emmental cheese, grated (about 2½ cups)
1/4 cup freshly grated parmesan cheese
1. Melt butter in a medium saucepan over medium heat. Whisk in flour and cook, stirring constantly, for about 3 minutes. Gradually add milk, stirring well until the mixture is smooth. Cook, stirring, until sauce is thickened.
2. Season with a little bit of salt and pepper. Remove from heat and whisk in mustard and nutmeg. Set aside while you make the sandwiches, or make the sauce up to 1 week in advance.
1. Preheat oven to 425° F. Line a baking tray with parchement paper and set aside.
2. Spread each bread slice with a layer of béchamel, spreading it all the way to the edges. Place 4 slices of bread, béchamel side up, on prepared baking sheet.
3. Top each with a piece of ham, a handful of gruyere, and a sprinkle of parmesan cheese. Place remaining slices of bread on top, béchamel side up, then top with remaining gruyere and parmesan cheese.
4. Bake at 425 degrees F for about 5-6 minutes, until cheese is melted, and then turn the oven to broil and broil until the cheese on top is lightly golden, 2-4 minutes.