Roast the Tomatoes:
Preheat your oven to 400°F (200°C). Arrange the sliced Roma tomatoes on a baking sheet, drizzle with olive oil, and sprinkle lightly with salt and pepper. Roast for 25–30 minutes, until caramelized and slightly shriveled.
Sauté Aromatics:
In a large pot, melt the butter over medium heat. Add the diced onion and cook for 5–6 minutes until translucent. Stir in the garlic and thyme, cooking for another minute until fragrant.
Add Roasted and Canned Tomatoes:
Add the roasted Roma tomatoes to the pot, followed by the crushed San Marzano tomatoes. Stir to combine and let simmer for 10 minutes to allow the flavors to meld.
Season and Simmer:
Add the sugar, salt, black pepper, and chicken stock. Bring to a gentle simmer and cook uncovered for 20 minutes, stirring occasionally.
Blend the Soup:
Using an immersion blender (or carefully transferring to a regular blender), puree until smooth and creamy. Return the soup to the pot if needed.
Finish with Basil and Cream:
Stir in the chopped basil and heavy cream. Simmer for another 2–3 minutes until warmed through.
Taste and Serve:
Adjust seasoning if needed and serve hot with a drizzle of olive oil or a sprinkle of parmesan.