01 -  Heat olive oil in a large soup pot over medium heat. Add chopped onion and cook until translucent, about 5 minutes. 
 02 -  Incorporate minced garlic and sauté for 1 minute, until fragrant. 
 03 -  Stir in crushed tomatoes, vegetable broth, dried basil, oregano, red pepper flakes, sugar, salt, and black pepper. Bring mixture to a gentle simmer. 
 04 -  Cook uncovered for 15 minutes, stirring occasionally to develop flavor. 
 05 -  Utilize an immersion blender or process in batches with a countertop blender until smooth. Return blended soup to pot. 
 06 -  Bring soup back to a gentle simmer. Add the orzo pasta and cook, stirring occasionally, until tender, 8 to 10 minutes. 
 07 -  Stir in heavy cream or whole milk for a richer texture. Adjust seasoning as necessary. 
 08 -  Butter one side of each bread slice. Layer cheese between two slices, keeping buttered sides outward. Cook sandwich on a skillet over medium heat until golden brown and cheese is melted, 2–3 minutes per side. Cool slightly and cut into bite-sized cubes. 
 09 -  Ladle hot soup into bowls. Top with grilled cheese croutons and sprinkle with chopped fresh basil to garnish.