Roast peppers by your preferred method (I put them in a 400 degree oven until blackened, then place into a plastic bag until cool) peel off blackened skin, seed and chop, set aside.
Heat oil in small pot over med high heat. Add onions, fry until browned. Add garlic and stir for about 1 minute. Add peppers and reduce heat to low. Let cook for a few minutes.
Add milk. Stir until heated through. Add cheese by handfuls, stirring constantly and letting the cheese melt between handfuls. Add more milk by the tablespoon until it gets to the desired consistency. Salt to taste and serve with tortilla chips and sliced jalepenos.