Cut five tortillas in thirds, then in thin strips, and spray with a butter-flavored spray. Toast in a 350° oven for about 8 to 10 minutes or until crisp. Set aside.

Place a medium skillet, preferably nonstick, over medium heat. One at a time, spray 7 corn tortillas with a butter-flavored spray. Using tongs, heat them on both sides in the skillet, turning often until softened. Place into 10-inch pie pan overlapping tortillas.

To make the sauce, generously coat a saucepan with a vegetable spray and cook the onions and mushrooms over medium heat, stirring constantly. Add the cayenne pepper, stir briefly, then add the chicken broth and bring to a boil. Dissolve the flour in skim milk and stir to remove all lumps. Add a little of the hot broth to the flour and stir in, then add the flour mixture to the broth and cook, stirring constantly, about 3 to 4 minutes. Add cream cheese, garlic salt, green chilies, and salt to taste. Stir to combine and set aside.

To cook the meat, heat the skillet again over medium heat. Add the beef and break up with fork, but allow it to sear until browned. Add onion and garlic and mix in well. Stir in the chili powder, spinach, and tomatoes. Season to taste with salt and pepper. Remove from heat and stir in egg substitute and 2 oz of the cheese. Put the beef on top of the prepared tortillas. Sprinkle with half the toasted tortillas, then the reserved sauce. Top with remaining grated cheese. Bake in a 325° oven for 30 minutes.

Garnish with remaining crisp tortillas on top.