Mushroom Strudel

I am very sorry about the lack of a picture to go with this recipe! If you want to see what these look like, please go to www.smittenkitchen.com/2008/05/mushroom-streudels/.
That being said, the recipe is from one of my favorite cooking blogs, Smitten Kitchen, but I made a few changes and had a few things turn out a little differently.
I originally found this while searching for a tasty appetizer to take to a dinner we were invited to. I needed something to serve to someone who is lactose intolerant, and it was surprisingly difficult to find an appetizer that didn't have cheese! These call for Parmesan, but I made some with the cheese and some without, and the ones without turned out just fine and were very tasty.
So, here's the recipe as I made it:
MUSHROOM STRUDEL
*Notes on phyllo: if you've never used it before, you may want to know that you will need to let it sit in the refrigerator to defrost about 7 hours, then on the counter for 30 minutes or so before you use it!
Small box of phyllo pastry (I used about 10 sheets)
1/2 c butter, melted
1 egg, beaten for egg wash
Filling:
1 pound cremini mushrooms (also called Italian brown mushrooms)
1 medium onion, minced
3 T butter
1 T chicken broth (recipe called for dry sherry but I don't use alcohol)
1 T flour
leaves from 1 sprig thyme
6 T freshly grated Parmesan (optional)
Kosher salt and freshly ground black pepper to taste

Preheat oven to 400F. Spray a baking sheet with nonstick spray or line with parchment. It helps to have a large work surface for this, like your kitchen table. Have all your ingredients ready and laid out before you get the phyllo out: melted butter, egg wash, filling, and cheese.
To make the filling: cook the onion in the butter until soft. Clean your mushrooms really well and slice fairly thin. If your mushrooms are large you may want to halve them before slicing. Add the mushrooms to the softened onion and saute until mushrooms are cooked through and some of the juices have begun to evaporate. Add the chicken broth (or sherry) and cook a couple of minutes more, until most of the liquid is gone. Stir in the flour, herbs, and salt/pepper to taste and let filling cool.
To assemble strudel: You'll need 2 damp dishcloths. Place one on the table, and use one to cover the remaining phyllo sheets as you work. Take one sheet of phyllo at a time from the package and place the remaining sheets between the damp cloths. Brush one half of the sheet at a time with butter. Carefully fold the unbuttered side over the buttered side and gently smooth out wrinkles and bubbles (doesn't need to be perfect). Repeat again, buttering half and folding it over, so the sheet is folded to 1/4 the size. You'll have one long column. Here I departed from the recipe the most. You can place a spoonful of filling, and fold triangular (like a flag) all the way up the column for one strudel per sheet of phyllo, or just place a spoonful of filling and fold over once in a triangle like a turnover and cut (a pizza cutter worked great), then repeat to get several strudel from one sheet (I did the latter--more filling to phyllo ratio worked for me!). If you use cheese, sprinkle each spoonful of filling on the phyllo with the cheese before folding the dough over. Then, brush the finished strudel with the egg wash and sprinkle more cheese on top. Place folded strudel on greased baking sheet. Bake 15 minutes until browned and crisp. Serve warm.