Pithivier is more a work of design than an absolute on how and what it’s made of. There are a few absolutes, though. It must be made with puff pastry. It must be circular. And it must have the rays of the sun etched into the top of the pastry so that, when baked, it represents a golden sun motif. Other than that, you can go your own way, fill it with all manner of sweet and savoury fillings, and make small ones or large ones.