Prepare the Soup:

• In a large pot, heat olive oil over medium heat. Add chopped onions and sauté until translucent, about 5 minutes.
• Stir in minced garlic and cook for an additional minute until fragrant.
• Pour in the canned tomatoes with their juices, breaking them up with a spoon.
• Add broth, sugar, and basil. Bring the mixture to a boil, then reduce heat and let it simmer uncovered for 15-20 minutes to allow flavors to meld.
• Use an immersion blender to puree the soup until smooth. Alternatively, carefully transfer the soup in batches to a blender and puree until smooth, then return it to the pot.
• Stir in the heavy cream and season with salt and freshly ground black pepper to taste. Keep the soup warm over low heat while preparing the croutons.

Make the Grilled Cheese Croutons:

• Heat a skillet or griddle over medium heat.
• Butter one side of each bread slice. Place two slices, buttered side down, on the skillet.
• Evenly distribute the shredded cheese on top of the bread slices in the skillet. Cover with the remaining two bread slices, buttered side up.
• Cook until the bread is golden brown and the cheese has melted, about 2-3 minutes per side.
• Remove from the skillet and let cool slightly. Cut the sandwiches into 1-inch cubes to create croutons.