brown and drain hamburger set aside. Put celery onion and carrots in butter cook until soft. add chicken broth add potatoes and hamburger cook until potatoes are tender. In small pot meet  3 Tbsp of butter and add 1/4 cup flour and mix and stir until it bubbles.  Add to pot to thicken and add 1 1/2 cups  of milk and 8 oz velveta cheese add salt and pepper to taste.  Take off heat add 1/4 cup sour cream