How to Make It
In a medium saucepan, toss together the cheese and cornstarch. Add the milk and chile and bring the mixture to a simmer, stirring constantly. Season with salt and pepper to taste.
In a large heavy skillet, heat the oil over medium high heat until hot, then stir in the on-ion, garlic, 1/2 teaspoon salt and 1/4 teaspoon pepper and cook, stirring occasionally, until golden, about 6 minutes. Stir in the chicken and cook until the chicken is cooked, about 5 minutes. Season the filling with salt and pepper to taste.
Preheat the oven to 350°F. Divide the filling between the tortillas. Roll each tortilla into a cylinder and place, side-by-side in a baking dish. Pour the cheese sauce over the tortillas and bake until hot, about 15 minutes. Sprinkle the cilantro over the enchiladas and serve.