Grown-up Mac and Cheese

Set a cast iron skillet or other heavy-bottomed skillet on medium low heat. Add mushrooms to the pan and drizzle some olive oil on them, and then sprinkle some salt and pepper. Toss them around and cook until the moisture dries up and mushrooms are roasted and turn deep brown in color. Remove mushrooms to a plate or bowl.

In the same skillet, sauté onions in 1 tablespoon of the butter, stirring occasionally, until golden brown and caramelized, about 15 minutes. Set aside.

Cook macaroni 1 minute shy of what is directed on the package. (So if the macaroni package says cook for 10 minutes, cook for 9 minutes.) Drain. This method of undercooking the macaroni ensures that the pasta does not get mushy when we bake it. Set aside.

To make the sauce, melt remaining 4 tablespoons butter in a large pot or saucepan over medium heat. Once butter is bubbly, add flour and whisk to combine. Cook until it is just light golden. Let the roux cook for a minute or so, whisking constantly. Then pour in milk and keep whisking. Cook this white sauce for about 4 to 5 minutes or until thick and bubbly. Add half-and-half, salt, pepper, nutmeg and mustard powder.

Preheat oven to 350ºF or 180ºC.

In a small bowl, whisk eggs and add about ¼ cup of the hot sauce, 1 tablespoon at a time, to temper the eggs. Keep stirring or whisking the eggs continuously as you pour in the sauce. The idea is to gradually increase the temperature of the eggs so that they do not curdle or cook when we add them to our pot of sauce. Pour the tempered eggs into the white sauce, whisking constantly as you add them. Add fontina, Gouda, and Parmesan cheeses. Stir until all the cheese melts.

Add cooked macaroni and mix. There should be enough sauce so that the pasta does not dry out after baking. Splash in a little milk, if needed, to thin the sauce.

For the topping, in a spice grinder or blender, grind bread slices to make breadcrumbs (you can use store bought breadcrumbs, about ½ cup). In a small bowl, combine breadcrumbs with olive oil and Parmesan cheese.

Generously butter a 9- by 13-inch baking dish. Lay on half the caramelized onions, half the macaroni, and half the mushrooms. Repeat the layers. Spread the breadcrumb cheese mixture on top, and bake until bubbly and hot, about 20 to 25 minutes.