3 tablespoons butter, plus more
10 oz fresh mushrooms, sliced
1 teaspoon chili powder
1/2 teaspoon salt
1/4 cup chopped fresh cilantro leaves
4 flour tortillas (10 inch)
2 1/2 cups grated Monterey Jack cheese
1/2 cup crumbled feta cheese
sour cream for a garnish (optional)
cilantro sprigs for a garnish (optional)
salsa for a garnish (optional)
Preheat the oven to 350 degrees.
Line a baking sheet with aluminum foil.
Melt 2 tablespoons of the butter in a medium skillet over medium-high heat.
Add the mushrooms, shake the pan to distribute them evenly in the pan, and then cook without moving them until the mushrooms begin to brown, about 5 minutes. Do not salt yet. Add more butter along the sides of the pan if the pan seems to be dry. Toss the mushrooms, and continue to cook them until they're nicely browned, about 2 to 3 minutes more.
Season the mushrooms with the chili powder and salt; cook 1 minute more.
Stir in the cilantro; set aside.
Toast the tortillas directly on a medium gas burner, turning occasionally until slightly blistered on each side. (If you have an electric stove, do this same method in a dry skillet.)
Place all 6 tortillas on the prepared baking sheet. Spread ~1/6 the Jack cheese on one half of each tortilla, top the Jack cheese with ~1/6 of the mushroom mixture; then sprinkle each tortilla with ~1/6 of the feta cheese.
Fold the other halves of the tortillas over the filling, to make a half moon shape.
Lay another sheet of foil over the top of the quesadillas to loosely cover.
Bake them until the cheese melts, about 12 minutes.
Serve them whole or sliced into wedges; top with any of the optional garnishes.