Special equipment: 8 by 8 inch baking dish
In a medium sauce pan boil the water, add the tomatillos and serrano chiles and let them cook for about 8 minutes. In a blender puree the tomatillos, chiles, garlic, and onions using enough of the tomatillo water to make a sauce consistency. Strain.
Cut the tortillas in half and then in quarters making 8 triangles from each one. In a medium-size skillet heat the oil, fry the tortillas until crisp and remove from heat.
In a medium-size skillet saute the chicken breast until done and then slice into 1-inch strips.
In a medium sauce pan bring the tomatillo salsa to a boil, taste for salt, and season if necessary, add the crispy tortillas and let simmer for about 4 minutes or until the tortillas get soft.
In a 8 by 8 inch baking dish, place some of the chilaquiles with sauce, add some of the chicken strips, cover with more tortillas then top with the grated cheese. Bake in a preheated 400 degree F. oven until the cheese melts, garnish with the cream, chopped onion, and avocado slices.