Butternut Squash Fettuccine Alfredo

butternut squash, cut in half and seeds removed (save seeds for roasting!)

olive oil

fettuccine or linguine (I use half whole wheat and half regular pasta)

pasta water, as needed

unsalted butter

all-purpose flour

low-fat milk, warmed in microwave for 1 minute

grated Parmesan cheese, divided

black pepper

salt