Preheat the oven to 400 degrees F.
Spray a baking dish with non-stick spray.
In a large skillet heat the olive oil over medium heat. Add the onion, garlic, pepper and mushroom and cook until soft, about 5 to 7 minutes.
Add the chicken and toss to combine.
Add 4 tablespoons enchilada sauce and mix. Remove from heat.
Arrange the tortillas in the pan and divide the filling up between them. Top each with a little cheese and wrap snugly.
Pour the remaining enchilada sauce over the top of the enchiladas and sprinkle with remaining cheese.
Bake for 18-20 minutes, until cheese has melted and enchilada sauce is bubbling.
Top with fresh pico de gallo, a dollop of sour cream and avocado slices. Serve with rice, if desired.