Triple Decker Tomato Grilled Cheese is made with three slices of bread, with one slice dipped in tomato soup, American cheese, and parmesan cheese.
Pour the condensed tomato soup into a wide, shallow, microwave-safe bowl. Heat it in the microwave for 2 minutes, stirring after every 30 seconds. Set aside. (You could also heat up the soup in a saucepan on the stovetop.)
Set out a piece of parchment paper. For each sandwich, take out three slices of bread. Generously butter one side of two slices of bread and place on the parchment paper.
Butter side down, add one slice of American cheese to one of the buttered slices of bread.
Submerge the unbuttered slice of bread into the bowl of soup. Add that piece of bread on top of the American cheese.
Top with 1 more slice of cheese, ¼ cup of the parmesan cheese, and the other slice of buttered bread (butter side up). Repeat this assembly for the remaining sandwiches.
Once assembled, place a sandwich in a pan that has a tight-fitting lid. Cover the pan with the lid and cook over low heat until golden brown (2-3 minutes), flip, and cook on the other side for 1-2 minutes.
Remove from the pan and serve immediately. Repeat with the remaining sandwiches.