Preheat oven to 350° F.

Wash hands with soap and water.

Before cutting, gently rub vegetables under cold running water.

Spray medium skillet with nonstick cooking spray. Add onion, mushrooms, and green pepper. Saute about 5-10 minutes over medium high heat until tender. Remove from heat.

Add shredded chicken, 1/4 cup enchilada sauce, and 1/2 cup cheese, either directly into the skillet or in a sepearate bowl if the skillet is not big enough. Mix well.

Spray an 8-inch by 8-inch baking dish with nonstick cooking spray.

Spread 1/4 cup enchilada sauce over the bottom of dish, then add 4 tortillas on top, spread out to cover entire dish.

Add half of the vegetable-chicken mixture to tortillas, then another 1/4 cup of enchilada sauce.

Repeat steps 7 and 8.

Cover casserole with remaining 4 tortillas, 1/4 cup enchilada sauce, and remaining 1/2 cup cheese.

Cover dish with foil and bake for 25 minutes.

Remove foil and bake additional 5-10 minutes, until all cheese is melted. Internal temperature of chicken should be 165°F with meat thermometer.

Cut casserole into 6 rectangles (3 x 2).