Chicken and Mushroom Quesadillas

Name: Chicken and Mushroom Quesadillas
Ingredients: 1/4 cup butter; 2 1/2 teaspoons chili powder; 2 garlic cloves, minced; 1 teaspoon dried oregano; 4 ounces fresh shiitake mushrooms, stemmed, sliced; 4 ounces button mushrooms, sliced; 1 1/2 cups shredded cooked chicken; 2/3 cup finely chopped onion; 1/3 cup chopped fresh cilantro; 2 1/2 cups grated Monterey Jack cheese; Olive oil; 16 5 1/2-inch-diameter corn tortillas