Parmesan cheese sauce

[Jinglepot]

I spotted a recipe for Pork fillet with the above sauce. Fresh cream was added to grated parmesan and looked runny initially ,but then was spooned onto the meat and appeared thick. (the partially cooked pork then finished off in the oven). Does the cream thicken up naturally like that when added to the cheese? Could you use creme fraiche instead do you think?