Fear not the bechamel
I have long believed that the Croque Monsieur is a nearly perfect food. For those of you who might be unfamiliar with this classic French open-faced sandwich, it is fairly simple: a slice of rustic bread, smeared with a combination of butter and Dijon mustard, a thin slice or two French jambon blanc (a very mild cooked ham with minimal salt), a scattering of nutty Gruyere cheese, all cooked until warmed through, then topped with a rich béchamel sauce and broiled.
Bread and ham and cheese, elevated with the creamy sauce into one of the best lunches imaginable. Add a little side salad or some thin, crispy fries and you are in heaven. A good one is ethereal, and even a mediocre one is pretty darned tasty. I think a lot of people are put off by the béchamel, but frankly, this is the easiest of the French mother sauces, and comes together in mere moments.
Looking to serve a version of this for brunch, I stumbled across a way to make it easily for a crowd, and breakfast it up a little bit. Using frozen square waffles instead of sliced bread allowed me to line the bottom of a casserole dish evenly, and then the rest came together quickly. The schmear of Dijon butter, the ham, and the grated cheese all gets popped into the oven until the cheese is melted and the dish is warmed through—which takes just long enough to pull together the béchamel. While the broiler heats up, you can top the casserole with the béchamel, then just a minute back in the oven to brown the sauce and you have a slice and serve version of this lovely dish that will be a terrific surprise on your next brunch buffet.
Even better, you can assemble the casserole and sauce up to two days ahead of time, and just heat for longer in the oven, and reheat the sauce the morning you want to serve. And if you want to up the ante, you can turn them into Croque Madames, by adding a fried egg on top of each slice before serving.
Croque Monsieur Casserole
4 square frozen waffles
1 tablespoon unsalted butter, at room temperature
1 tablespoon Dijon mustard
8 ounces thinly sliced mild ham
1 cup grated Gruyere cheese (or other nutty Swiss-style cheese)
1 cup whole milk
1 ½ tablespoons unsalted butter
1 ½ tablespoons all-purpose flour
Salt and pepper
Preheat your oven to 400°F degrees with a rack in the top third, and prepare a 9" square baking dish with nonstick spray.
Line the bottom of the baking dish with the waffles; it is fine if they are still frozen. In a small bowl, blend the mustard and butter to a smooth paste, and spread a thin layer evenly over the waffles. I find a pastry brush works best for this. Top the buttered waffles with an even layer of the ham and then sprinkle the grated cheese over the top. When the oven is ready, pop the casserole in, and set a timer for 10 minutes.
While the casserole is cooking, melt the butter in a small saucepan over medium high heat. When the butter has stopped foaming, add the flour and whisk quickly to combine, letting it cook for one minute. Add the milk slowly, whisking constantly to prevent lumps forming, and to blend the milk into the butter and flour. Bring to a boil, whisking constantly and let cook until thickened to the consistency of loose pudding. Remove from the heat and season to taste with salt and freshly ground black pepper. Set aside.
When the cheese is fully melted and the ham and waffles are warmed through, remove the dish from the oven and turn the broiler on high. Spread the béchamel sauce evenly over the casserole. When the broiler is heated, return the casserole dish to the oven and, leaving the door slightly ajar, watch carefully for 1 minute or so until the béchamel browns lightly. Remove from the oven and serve hot, with or without a fried egg on top.