12 to 18 sheets phyllo pastry (12 to make four large strudel, 18 to make smaller triangles)
1/4 to 1/2 cup butter, melted (1/4 cup to make large strudel, 1/2 cup to make smaller triangles; alternately, you could use olive oil for a different flavor profile)
1 egg, beaten (for large strudel; I did not see the need to seal the small ones)

1 pound mixed, fresh, wild and cultivated mushrooms (we used only creminis, and ended up with plenty of flavor. If you omit the stems, start with 1.5 pounds)
1 medium onion, minced
3 tablespoons butter
Freshly grated nutmeg (optional, we skipped it)
1 tablespoon dry sherry
1 tablespoon all-purpose flour
Leaves from 1 sprig marjoram or thyme
4 to 6 tablespoons freshly grated Parmesan, plus extra for sprinkling, if you wish (the latter amount for the minis)
Salt and pepper to taste