First you’ll need to roast the chiles. Place the chiles under the broiler until blackened, about 5 minutes per side. Place the chiles in a paper sack or plastic food-storage bag, close it tight and let the chiles steam for 20 minutes. Take the chiles out of the bag and gently rub off the skin. Remove the stem and seeds, then chop the chiles.
Add the cream cheese and evaporated milk to a saucepan, then over medium-low heat melt and blend the two while stirring. After 5 minutes, the cream cheese should be melted and blended with the evaporated milk. Stir in the chopped chiles, then taste and add salt (I start with 1 teaspoon and go from there). Serve warm.
Notes
If you prefer to used canned green chiles, you'll need 8 ounces.