For best results, use good quality all-butter puff pastry and crisp, unbruised apples. Ensure pastry is thawed but cold for optimal flakiness. For faster prep, use pre-sliced apples or a mandoline. If apples are not tender, slice thinner next time or cover with foil during baking. If caramel is too runny, it will thicken upon cooling; if still too thin, return to a low oven briefly. Ensure a generous butter and caramel base to prevent sticking.