2 tablespoons olive oil
1/2 onion, chopped in a medium dice
1 carrot, chopped in a medium dice
1 celery stick, chopped in a medium dice
3 garlic cloves, smashed
4 cups vegetable broth
2 15-ounce cans diced tomatoes, with juice
2 teaspoons Italian seasoning
3 tablespoons sugar
Salt, to taste
Ground black pepper, to taste
1/4 cup butter, softened
1 teaspoon garlic powder
8 slices white bread
1 cup mozzarella cheese, grated
Place olive oil in a large Dutch oven or stock pot and heat over medium heat. When hot, add onion, carrot, celery and smashed garlic cloves. Cook for about 3 minutes, until the vegetables start to sweat and become aromatic.
Add the vegetable broth, cans of diced tomatoes, Italian seasoning, sugar, salt and ground black pepper. Bring to a boil and reduce heat to a simmer. Let simmer for 30 to 45 minutes. Taste and adjust seasoning if necessary.
In a small bowl, combine the softened butter with the garlic powder. Preheat the broiler.
Butter one side of each slice of white bread with the garlic butter. Place one slice of bread on a baking sheet, butter side down, and top with about 1/4 cup of mozzarella cheese. Place another slice of bread, butter side up, on top of the cheese. Repeat with remaining slices of bread and cheese to make four sandwiches.
Place the sandwiches under the broiler for about three minutes or until the bread is golden brown. Remove from the heat, flip and broil for another three minutes, until the other side of the bread is also golden brown.
Slice the sandwiches in half and serve with the tomato soup.