Melt butter, stir in flour, salt, pepper, cumin and
dry mustard. Cook and stir over medium heat until bubbly. Remove from heat,
blend in milk with wire whisk. Cook and stir again over medium heat until mixture is
thick and bubbly.
Stir in cheeses until they are melted. Remove from heat, add slowly to beaten egg
yolks (start with a spoonful at a time, mixing thoroughly with each addition so as to not
cook the eggs). Stir in the green chile.
In separate bowl, beat the egg whites with cream of tartar in large mixing bowl until
stiff but not dry. Gently fold the cheese mixture into the egg whites. Pour
into ungreased 2-quart soufflé dish. Bake at 350 degrees for 50-55 minutes.
(Do not open the oven door while baking.)