This soup was just terrific, cheeses and hearty, perfect on a February evening. I followed the ingredients precisely, but changed the cooking instructions because 15 oz. of broth is not enough liquid for the 1/4 cup of flour. This will burn and stick to the bottom of your pot.
Here is what I did:
Melt 3 TBSP butter in Dutch oven over medium high heat, add mire poix ( carrots celery and onion) and sweat for 10 minutes. Add flour and mustard powder and let cook for a few minutes. Add all remaining ingredients except cheese and bring just to a simmer, reduce heat to low and cover with a lid. Cook for 30 to 45 minutes until potatoes are tender, stirring occasionally to keep from sticking to bottom. Add grated cheese and adjust seasoning with salt and pepper.