1 sm. onion, chopped fine
1 1/2 tbsp. unsalted butter
1 (3 oz.) can chile, drained and chopped (about 2/3 c.)
3 oz. Cheddar cheese, cut in bits
1 (14 oz.) can plum tomatoes, drained, seeded, and chopped (about 2/3 c.)
1/2 c. chicken broth
3/4 c. Half and Half
Cayenne to taste

Saute the onion in butter until soft; add chile and tomatoes. Cook over moderate heat for 8-10 minutes or until liquid is evaporated. Stir in Cheddar cheese over low heat and stir until melted. Stir in broth, Half and Half, cayenne, and salt to taste. Do not boil.