One-Pot Pumpkin Mac and Cheese

Place a rack in upper third of oven and preheat to 350°. Toss together 12 oz. Monterey Jack, coarsely grated (about 3 cups), and 8 oz. Gruyère, coarsely grated (2–3 cups), in a large bowl with your hands. Add 2 Tbsp. cornstarch and toss again until each piece of cheese is thoroughly coated. Set cheese mixture aside.

Melt 2 Tbsp. unsalted butter in a large (14-cup capacity or more) high-sided ovenproof skillet, rondeau, or short pot over medium-high heat. (If you don’t have any of those options, you can use a large Dutch oven.) Add 4 garlic cloves, finely chopped, 1 Tbsp. finely chopped thyme, and ¼ tsp. crushed red pepper flakes and cook, stirring often, until fragrant, about 2 minutes. Add 4½ cups water and bring to a simmer. Add 1 lb. lumache (snail shells) or other medium shell pasta and cook, stirring often to prevent pasta from sticking to the bottom of skillet, until about two thirds of liquid has been absorbed and pasta is very al dente, about 5 minutes.

Reduce heat to low and stir one 12-oz. can evaporated milk, 2½ tsp. Diamond Crystal or 1½ tsp. Morton kosher salt, 1 tsp. freshly ground pepper, and ¼ tsp. ground nutmeg into pasta. Add reserved cheese mixture a handful at a time, stirring after each addition until mostly melted before adding more. Remove pan from heat and stir in one 15-oz. can unsweetened pumpkin purée. Taste and season with more salt if needed. (If you used a Dutch oven, transfer pasta to an ovenproof baking dish.)

Top mac and cheese with remaining 6 oz. Gruyère, coarsely grated (1–2 cups), and tightly cover with foil. Bake 20 minutes.

Heat broiler. Uncover and broil just until top is browned, 2–6 minutes, depending on your broiler. (Keep a close eye on it to prevent burning.) Let cool slightly, then top with thyme leaves.