Brown ground steak in large saucepan or nonstick skillet over medium heat 8 to 10 minutes or until beef is not pink, breaking up into 3/4-inch crumbles. Pour off drippings.
Add soup and amount of water according to soup can directions. Stir in thyme; bring to a boil. Reduce heat; simmer, uncovered, 5 minutes to blend flavors, stirring occasionally.
Cut cheese to fit bread slices; top bread with cheese. Place bread slices on rack in broiler pan so surface of bread is 3 to 4 inches from heat. Broil 1 to 2 minutes or until bread is toasted and cheese is melted and golden brown.
Evenly ladle soup into 4 bowls. Top each bowl with 1 bread slice.