Preheat the oven to 425°F (220°C). This higher heat will caramelize the tomato sugars quickly, developing deeper flavor and slightly charred edges that add smoky notes.

Core and halve the tomatoes. Place them cut-side up on a rimmed baking sheet. Drizzle with 1 tablespoon olive oil and season lightly with 1/2 teaspoon kosher salt. Roast for 30–35 minutes until the edges are deeply browned and skins blistered. Why: roasting concentrates flavor and reduces water so the soup is richer and not watery.

While the tomatoes roast, heat a heavy-bottomed Dutch oven over medium heat. Add 1 tablespoon olive oil and the butter. Swirl to melt the butter into the oil; the oil raises the butter’s smoke point and the butter adds a silky mouthfeel and flavor base.

Add the diced onion and a pinch of salt. Sweat the onion over medium heat for 6–8 minutes until translucent and beginning to caramelize at the edges. Why: sweating (gentle cooking) draws out sweetness and builds the aromatic base without browning too quickly.

Add the minced garlic and cook 30–45 seconds until fragrant. Add the tomato paste and toast it for 60–90 seconds, stirring constantly. Why: toasting tomato paste develops concentrated umami and removes the raw, metallic taste of paste.

Deglaze the pot with the balsamic vinegar, scraping up any browned bits. The vinegar lifts the browned fond (concentrated flavor) and adds a bright, sweet-acid balance to the soup.

Remove the roasted tomatoes from the oven and transfer them (including any pan juices) to the pot. Add the vegetable stock, dried basil, fresh thyme sprigs, bay leaf, the remaining 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Stir to combine.

Bring to a gentle simmer, then reduce heat and simmer, uncovered, for 12–15 minutes. Why: a short simmer lets the flavors marry without over-reducing the liquid; it also gives the herbs time to infuse.

Remove and discard the bay leaf and thyme stems. Use an immersion blender to purée the soup until silky smooth; alternatively transfer in batches to a high-speed blender. Important safety note: if blending hot soup in a blender, vent the lid slightly and cover with a towel to prevent pressure build-up and splattering.

For restaurant-smooth texture, pass the blended soup through a fine-mesh sieve or chinois into a clean pot, pressing with a ladle or spatula to extract as much liquid as possible. Why: straining removes seeds and any fibrous bits for an elegant, velvety mouthfeel.

Return the strained soup to gentle heat. Stir in the sugar (to balance acidity), heavy cream, and adjust seasoning with salt and pepper to taste. Warm through (do not boil once cream is added) — 2–3 minutes. Why: finishing with cream softens acidity and adds luxurious richness; avoid boiling to prevent cream separation.

Ladle into warmed bowls, garnish with torn fresh basil leaves and a thin drizzle of olive oil or a small swirl of cream. Serve with crusty bread or grilled cheese croutons for an elevated comfort experience.