Hudson's was a department store in Michigan which is now owned by Marshall Fields. Hudson's had darling little cafes inside their stores, and one of their specialties was this amazing cheddar cheese soup. It's the best I've ever had, and I think you will agree! Angostura bitters is a surprise secret ingredient that really adds to the flavor. Be sure to use good quality, sharp aged (12 months or more) cheddar. It is absolutely KEY to the success of this recipe.