Preheat a skillet over medium heat.

Butter one side of each slice of bread.

Place one slice of bread, butter side down, on the skillet.

Add the cheese slices on top of the bread in the skillet.

Top with the second slice of bread, butter side up.

Grill the sandwich until the bread is golden brown and the cheese is melted, about 3-4 minutes per side.

Meanwhile, in a saucepan, combine the can of tomato soup and 1 cup of water or milk. Stir and heat over medium heat until warm.

Serve the grilled cheese sandwich with the warm tomato soup.