In a greased 9-in. pie plate, arrange tortillas in an overlapping pattern so that they cover sides and bottom of pie plate, forming a crust. Set aside.
In a large skillet, cook chorizo over medium heat until fully cooked; drain and set aside. In the same skillet, saute mushrooms in butter until tender. Add onion, salt and pepper; cook 2 minutes longer.
In a large bowl, combine the eggs, half of the cheese, chorizo, cream, tomato, garlic powder and cumin. Stir in mushroom mixture. Pour into pie plate; top with remaining cheese. Cover edges of quiche with foil so tortillas do not burn.
Bake at 350° for 40-45 minutes or until a knife inserted in the center comes out clean. Let stand for 10 minutes before cutting. Serve with salsa and avocado if desired.