use a pot that can go from the stovetop to the broiler. saute scallions and garlic in butter until soft. add chorizo and chili powder and cook for 10 minutes. add tomatoes and simmer for 10 minutes. add broth, salt and pepper. bring to boil, stir in vermicelli, lower heat and cook uncovered until all liquid is absorbed. sprinkle with the cheese and place in broiler until cheese melts and is golden brown.