Directions:

To cook the pasta & mushrooms:

Preheat oven to 425ºF 

Cook the pasta in a pot of salted boiling water large enough to keep the pasta from boiling over but small enough to use for sautéing mushrooms and making your sauce. This is just to avoid dishwashing. You can also use several pots and pans.

Cook the pasta until it’s barely al dente or slightly chewy. It will continue to cook in the oven. Drain and set aside.

In the same pot, melt the 2 tablespoons of butter in a sauté pan and sauté the mushrooms until just tender. Season to taste with salt and pepper and add the mushrooms to the pasta, setting some of the mushrooms aside for a garnish.

To make the sauce:

Don’t clean the pot but rather heat the 3 Tbls butter over medium heat. 

Whisk in the flour and cook, constantly whisking, until the flour is foamy and just starting to turn a light golden, about 4 minutes. 

Slowly whisk in the milk or broth and continue whisking until the sauce thickens and is creamy, 3 to  4 minutes. Taste it to see if it’s pasty or tastes like flour. If so, whisk and cook for a few minutes more.

Season to taste with nutmeg, salt, white pepper, and thyme. 

Turn off the heat and add the grated cheese, whisking to blend until the cheese is completely melted. (The sauce will seem thick at first and thin out as the cheese melts; it will thicken while it bakes.) 

Add the cooked pasta and mushrooms, stirring to coat well.

Make the optional topping: 

Combine bread crumbs, melted butter, and Parmesan, if using, and parsley in a medium bowl. Season with salt and pepper and, using your hands, mix well to ensure the bread crumbs are evenly coated. 

Finishing & Baking:

Transfer the macaroni and cheese mixture to your buttered baking dish, leaving the mixture “rustic,” with the pasta looking craggily. In other words, don’t flatten it. 

Scatter the bread crumb topping, if using, evenly over the top. Place on a baking sheet that is covered with foil or parchment in case the sauce bubbles over.

Bake until the mixture is bubbling, has thickened, and is creamy. The bread crumbs should be evenly golden brown, 25 to 30 minutes. 

Let cool slightly before serving.

Dust with fresh parsley.