Brush the butternut with olive oil, season with salt, tuck in garlic cloves and roast at 180C for 35-40 minutes until soft.
Scoop the flesh out and blend together with stock or water and ricotta or cream, if using, until smooth. Add a couple of garlic cloves (optional).
While the squash is roasting, cut the chorizo into slices. Heat a large pan to medium and fry the sausage until crispy, then transfer to a plate. It will produce a lot of oil, wipe most of it off the pan or otherwise the sauce will be too greasy.
Boil pasta to one minute short of al dente and reserve a cup of cooking water.
Return the squash and chorizo back to the pan and warm through. Taste and adjust for salt.
Add the pasta, toss to combine and adjust the sauce consistency with the reserved pasta water. Cook for about a minute until the pasta reaches al dente.
Serve sprinkled with grated parmesan and fresh chopped parsley.