The pastry puffs can be frozen. Thaw them and then reheat in a 350 degree F (180 degree C) oven for 5 to 10 minutes, or until crisp. Cool before filling. Choux pastry rises due to the egg content and steam. Therefore, it is essential that the oven is hot when you add the pastry puffs. Without this initial burst of steam they will not rise properly or dry out; they will stay flat and become soggy.