Preheat oven to 400°F.
Place a large pot of water over high heat and bring up to a boil to cook the pasta. Once at a boil, add some salt and the pasta and cook until al dente, according to package directions. Drain pasta thoroughly, return it to the pot and reserve.
In a large skillet over medium-high heat, heat 1 turn of the pan of EVOO and the butter. Cook garlic and onion until tender, about 2-3 minutes. Sprinkle in flour and cook for another minute then whisk in chicken stock and half-and-half, season with salt, ground black pepper and nutmeg. Bring it up to a bubble and thicken.