Preheat oven to 400 degrees F.
Place tomatoes cut side up with the onion, carrots and garlic on a rimmed baking sheet or oven safe dish. Drizzle with oil and sprinkle salt and pepper over the top.
Roast for 40-50 minutes, until tomatoes are slumped looking, turning golden brown, and other veggies are roasted and browned.
In a heavy bottomed pot or dutch oven, add the roasted vegetables, San Marzano crushed tomatoes (juice and all), chicken stock, and fresh herbs. Bring to a low simmer over medium-low heat, then add bay leaf. Cook for 20-25 minutes.
While tomato soup is cooking, make grilled cheese croutons by spreading butter on outer sides of the bread and placing two slices of cheese in the middle. Press sandwich between a panini press, or cook on a pan over medium heat, flipping when bread is browned.
Cut the sandwiches into 1 or 2 inch squares. To make them crunchier, like a crouton, put sandwich squares onto an oven safe baking sheet or dish and set oven to 200 degrees until soup is complete OR until the croutons have come to your preferred crunchiness.
Once soup has cooked for 20-25 minutes, taste and season with sugar (tomato soup can be acidic) and salt and pepper to taste. Carefully transfer soup to a blender, removing thyme stems and bay leaf, and puree soup until there are no large chunks left, then strain through a fine mesh sieve into a bowl or pot so ensure smooth soup.
Serve with grilled cheese croutons immediately. Add a drizzle of cream to each bowl as desired.
Store soup in an airtight container in the fridge for up to 5 days or in the freezer for up to 3 months.