Heat oven to 350°F. In large bowl, stir cracker crumbs and 1 cup of the soup until well mixed; let stand 10 minutes.
Add beef, salt, thyme, pepper and egg to cracker crumb mixture until well mixed. Spread half of beef mixture into ungreased 8x4-or 9x5- inch loaf pan. Cut 3 slices of the cheese into 1/2-inch strips. Arrange strips in center of loaf to within 1/2-inch of sides and ends of pan. Top cheese with remaining beef mixture covering completely to sides of pan.
Insert ovenproof meat thermometer so tip is in center of loaf. Bake uncovered 1 hour to 1 hour 15 minutes or until beef is no longer pink in center and thermometer reads 160°F. Arrange remaining cheese slices, overlapping, on top of meat loaf. Top cheese with 1/4 cup of the remaining soup (making sure to get onion pieces). Bake an additional 5 minutes or until cheese is melted. Let stand 5 minutes; remove from pan. Heat remaining soup until hot, serve with meat loaf and potatoes.