You want to work as quickly as possible to keep the dough from drying out so you don't need to do the whole moist towel cover up thing.
Rinse asparagus and dry well. Cut bottom ends off and discard. If you have thick asparagus you can use a potato peeler and peel about 1/2 way up the stalk so it's not fiborous when eating.
Lay the phyllo dough flat on your work space, spray completly with butter spray, lay 3 or 4 pieces of asparagus (depending on their size)at the far right of the dough with 1/3 the stalk over the top edge, sprinkle with parmesan cheese then fold the bottom of the 2 or 3 pieces of dough (i like 2 my husband likes 3 so it's more bready less vegtable flavor) up over the asparagus like tucking into bed, then from right to left roll it all the way to make the bundle, spray outside totally with butter spray and lay on parchment lined baking tray and repeat until you use all the dough and asparagus. It usually works out just about right but towards the middle I decide if I need to increase the asparagus to dough ratios so i use the whole thing because they heat up nicely the next day too.
sprinkle all with garlic powder (not garlic salt cause the cheese and butter make it salty enough) then sprinkle cheese on top of the pastries.
Bake at 350 until golden brown about 15-20 minutes.