Take an oven pan and line it with parchment paper before placing the puff pastry on it. Depending on the length of the asparagus you might need to roll out the dough slightly more.
Perforate the dough with a fork and bake in the oven for 15 min
Chop the bacon and fry it
Cut away the lower harder part of the asparagus
Grate the cheese
Take the puff pastry out of the oven and spread the cheddar cheese over it, then bacon, asparagus and finally the parmesan cheese and some freshly ground black pepper.