Butternut Squash Mac & Cheese

1 pound macaroni with lines, the girls love bow-tie
Salt
1 tablespoon extra-virgin olive oil
2 tablespoons butter
1/2 medium onion
2 tablespoons chopped fresh thyme leaves,
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
1/4 teaspoon ground nutmeg
Black pepper

Heat a pot of water to boil for the pasta. Salt the water then add the pasta and cook to al dente.
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. 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.(If you have a immersion mixer, us it! If not, I always put the stock and squash into the blender and get it smooth before hand, it saves a lot of time and there are no lumps.) 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.
Drain cooked pasta well and combine with sauce.