Melt butter; saute onions until translucent. Add garlic, salt, chilies and tomatoes.
Cut up cheese; add evaporated milk until consistency resembles thick gravy.
Cook slowly, adding milk a little at a time. Stir often.
Hot chilies may be added if hotter than mild Con Queso is desired. Pimento paprika or achiote may be added for color.
Serve with corn chips or Tostitos as a dip or cut corn tortillas into 6 preshaped wedges and fry in hot fat until crisp.
Serves 8-12.