1. Cook pasta in salted boiling water until al dente, about 7-8 minutes, then drain and reserve 1/2 cup pasta water.

2. Melt butter in a medium saucepan over medium heat, whisk in flour and cook for 1 minute to form a roux.

3. Gradually whisk in milk until sauce thickens and becomes smooth.

4. Reduce heat and stir in cheddar and Parmesan cheese until melted and creamy.

5. Stir in pumpkin puree, nutmeg, salt, and pepper until evenly combined.

6. Fold cooked pasta into the sauce, adding reserved pasta water as needed to reach desired consistency.

7. Optional: transfer mixture to a casserole dish, top with breadcrumbs and extra cheese, and bake at 375°F for 15-20 minutes until golden.

8. Serve hot with desired side dishes.