You can use this with apples or pears. Variation below. If using apples, be sure to use firm ones, preferably granny smith or golden delicious. To thaw puff pastry, thaw overnight in the fridge (preferred method). If you don't have that kind of time, thaw on the counter for 30-60 minutes. It should unfold easily, but feel firm. If seams crack, rejoin by rolling them smooth with a rolling pin. If the dough gets too warm and softens, place it in the freezer until firm again.