Step 1

Preheat oven to 450f and set one rack to the second-lowest position and the other to the middle of the oven. Toss mushrooms with olive oil, thyme, salt, and pepper. Spread out mushrooms on a baking sheet and roast on the lower rack for 15-20 minutes or until well browned. Don't overcrowd the mushrooms. Use two sheets if necessary.

Step 2

Meanwhile, bring a pot of salted water (2 tablespoons kosher salt) to boil and cook the rigatoni until very al dente. About 2 minutes less than package instructions.

Step 3

Cook spinach for 30 seconds in boiling water and drain. Once able to handle, squeeze the water out then chop. In a large bowl mix together the spinach, nutmeg, heavy cream, ricotta, Fontina cheese, 1/4 cup Parmigiano Reggiano, garlic, and the roasted mushrooms.

Step 4

Add the pasta to the bowl and mix once more. Taste test and adjust salt and pepper to taste. Place contents of the bowl in a 9 by 13 baking dish. Top with the remaining Parmigiano and bake for 15 minutes covered. Covering with parchment paper then foil will prevent sticking.

Step 5

After 15 minutes remove covering and bake for 5 minutes more until golden. For even more color broil for the last 1-2 minutes but watch very carefully.

Step 6

Wait 15 minutes before serving so that the cheese settles. Enjoy!