Boo's Butternut Squash Mac-n-Cheese

1 pound macaroni with ridges
1 tbsp extra-virgin olive oil
2 tbsp unsalted butter
2 tbsp chopped fresh thyme, plus a few sprigs for garnish
1/2 medium onion
3 tbsp all-purpose flour
2 cups chicken stock or broth
1 10-ounce box frozen cooked butternut squash, defrosted
1 cup cream or half-and-half
2 cups (8 ounces) grated sharp Cheddar cheese
1/2 cup grated Parmigiano-Reggiano
1/4 tsp nutmeg
Freshly group pepper and coarse salt to taste

Cook the pasta.

While the pasta cooks, heat a medium heavy-bottomed pot over medium heat. Add the oil and butter. When the butter melts into the oil add the thyme and grate the onion directly into the pot with a handheld grater or Microplane. Cook the grated onions for a minute or two and then add the flour and cook together for a minute or two more. Whisk in the stock and add the butternut squash and cook until warmed through and smooth. Stir in the cream and bring the sauce to a bubble. Stir in the cheeses in a figure-eight motion and season the sauce with salt, nutmeg, and pepper to taste.

Drain the cooked pasta well and combine with the sauce. Garnish with thyme leaves and an optional sprinkle of cheese. (Boo is the author's dog.)

-Rachel Ray, 365: No Repeats