For this cheesecake, it’s very important that the cream is whipped to stiff peaks. That means that when you lift up the whisk, the cream stands up stiffly without flopping off. If you use cream that is still sloppy and not quite so stiff, you will end up with a cheesecake that won’t set.  Be careful not to overwhip the cream because then it’ll turn into butter. As a rule of thumb, once the cream starts to thicken up to a thin yogurt consistency, I keep a very close eye on it because it will thicken to stiff peaks very quickly. If you’re using a stand mixer or electric mixer you can finish it off with a hand whisk to make sure that it doesn’t overwhip.