This is a Rachel Ray recipe. It's one of the few recipes that I follow as directed. Well, except that I can't find frozen butternut squash, so I make my own. I just steam a whole butternut squash and then pack in ziplocks and freeze until I need it. An example of why you should have a kitchen scale. If you don't have one, get one! You won't regret it.
Anyway, you can't really taste the butternut squash, so this is an excellent way to sneak in some ... well I was going to say veggie, but I just looked it up and apparently it's a fruit. Weird. Fruit in mac and cheese? Well, it works anyway.
1 pound macaroni with lines, such as tubatini or mini penne rigate
1 tablespoon extra-virgin olive oil, 1 turn of the pan
2 tablespoons butter
1/2 medium onion
2 tablespoons chopped fresh thyme leaves, plus a few sprigs for garnish
3 tablespoons all-purpose flour
2 cups chicken stock
1 (10 ounce) box frozen cooked butter nut squash, defrosted
1 cup cream or half-and-half
2 cups (8 ounces) sharp Cheddar, grated
1/2 cup grated Parmigiano-Reggiano, a couple of handfuls
1/4 teaspoon ground nutmeg, eyeball it
Heat a pot of water to boil for the pasta. Salt the water then add the pasta and cook to al dente or, with a bite to it.
While pasta cooks, heat a medium heavy bottomed pot over medium heat. Add the extra-virgin olive oil and butter. When the butter melts into the oil, add the thyme and grate the onion directly into the pot with a hand held grater or Microplane. Cook the grated onion in butter and oil 1 to 2 minutes, then add flour and cook together 1 to 2 more minutes. Whisk in stock, then combine with butternut squash until warmed through and smooth. Stir in cream or half-and-half and bring sauce to a bubble. Stir in cheeses in a figure 8 motion and season the completed sauce with salt, nutmeg and pepper. Taste to adjust seasonings.
Drain cooked pasta well and combine with sauce.