Cook ground beef in a large stock pot over medium-high heat about 3 minutes, stirring until meat crumbles. Add onions and next 4 ingredients and sauté 4 minutes or until beef is no longer pink. Drain well.
Stir in chicken broth and potatoes. Bring to a boil; cover, reduce heat, and simmer 10 to 12 minutes or until potatoes are tender.
Melt butter in a nonstick skillet over medium heat. Stir in flour, and cook, stirring constantly, 2 to 3 minutes or until flour is lightly browned. Whisk flour mixture into simmering beef mixture; bring to a boil. Reduce heat, and simmer 6 minutes or until thickened.
Whisk in cheese and next 3 ingredients, just until cheese melts.
Separate hotdog buns in half; brush each half with melted butter. Cut each piece in half lengthwise and widthwise. Bake at 400°, buttered side down, on a lightly greased baking sheet 5 to 10 minutes or until golden brown. Serve immediately with soup.