Gluten-Free Croque-Monsieur

Ingredients

• 8 slices gluten-free white sandwich bread, homemade or store-bought
• 2 tablespoons unsalted butter
• 3 tablespoons sweet rice flour
• 2 1/2 cups whole or 2% milk, warmed
• 1/4 teaspoon salt
• 1/2 teaspoon freshly ground black pepper
• 8 ounces Gruyère cheese, grated
• 1/4 cup freshly grated parmesan cheese
• Dijon mustard
• 1/2 pound thinly sliced ham

Directions

1. Set your oven to 425ºF. Arrange the bread slices on a rimmed 18 by 13-inch baking sheet. Bake until the bread is just starting to color, turning the slices once along the way. Take the pan out and keep it nearby, but leave the oven on.
2. For the sauce, melt the butter in a small pot. Whisk in the sweet rice flour, then keep whisking for 3 minutes while it cooks; the mixture should become lightly golden. Pour in the warm milk gradually in an even stream. Keep whisking until the sauce starts to bubble, then season with salt and pepper.
3. Add 1/4 cup of the Gruyère plus all the parmesan, and whisk until the sauce is smooth.
4. Build the sandwiches right on the baking sheet. Give each piece of bread a thin swipe of mustard. Arrange a few slices of ham and a generous sprinkle of Gruyère on 4 of the bread slices, holding back about one-quarter of the cheese. Close each sandwich with a second slice of bread, with the mustard facing down. Spoon plenty of white sauce over each sandwich, then scatter the remaining Gruyère on top.
5. Put the sandwiches back in the oven. Bake for 5 minutes, just to heat them through.
6. Switch on the broiler. Broil until the cheese has melted, bubbled, and taken on a little light brown color. Serve right away.