Fill a pot with water and add the chicken.
Simmer for 30 to 40 minutes or until no pink remains in the middle, then drain and shred with a pair of forks.
Put it back in the pot.
While the chicken cooks, line a baking sheet with foil and arrange the chilies on there.
Broil them on high for 15 minutes on each side or until blackened.
Put them in a bowl and cover it with foil. Leave them for 20 minutes.
Peel the skin off them, discard the stems and seeds, and cut into short thin strips.
Add the soup, milk and chilies to the pot with the chicken and cook for 20 minutes.
Preheat the oven to 350°F.
Line the bottom of a 9 x 13-inch baking pan with 3 rows of 3 tortillas and then add a layer of casserole filling and cheddar cheese.
Add a layer of 2 rows of 3 tortillas and then the filling and cheese, and repeat once more.
Bake for 30 minutes.
Let it cool for 5 minutes and then serve, perhaps paired with chopped tomatoes and lettuce.
Enjoy!