I have not tried this recipe yet, but it looks good to me.
1 cup cheese (Monterey Jack, Asadero or Chihuahua) shredded fine
4 ounces green chiles
1/4 cup Half & Half
2 tablespoons onion, chopped fine
2 teaspoons ground cumin
1/2 teaspoon salt
1 serrano pepper, chopped fine (optional)
1 tablespoon fresh cilantro, chopped fine (optional)
Put all ingredients in a double boiler and heat on medium. Cook until melted and well blended, stirring occasionally. Serve with fresh tostadas or hot flour tortillas.