Place 4 bread slices on a work surface; arrange 1/2 cup cheddar cheese on each slice. Top each slice with 2 tomato slices and 1 tablespoon basil. Top with remaining 4 bread slices.
Heat a large nonstick skillet over medium heat. Coat pan with cooking spray. Add sandwiches to pan; cook 4 minutes or until lightly browned. Turn sandwiches over; cover and cook for 2 minutes or until cheese melts.