Break up ground beef with a fork in a large skillet. Add onion and cook over medium heat until meat loses pink color, stirring frequently. Add tomato soup, water, salt, parsley, and TABASCO® Sauce. Bring to a simmer, reduce heat to low, and cook 15 to 20 minutes, stirring occasionally.
Cut letters from cheese slices to make names or initials. Spoon hamburger mixture over bottom halves of toasted buns and decorate with cheese names or initials. Top with remaining bun halves.
Makes 6 servings.