This roasted tomato basil soup is bright, silky, and deeply savory—caramelized fresh tomatoes and onions, mellow roasted garlic, and a shower of fresh basil blended until smooth. The texture is velvety thanks to a high-powered blender and a short simmer to concentrate flavor.

Plan about 30 minutes active prep plus the roast and a 40-minute simmer; the recipe yields Servings: 8 large bowls and is ideal for cozy weeknight dinners, make-ahead lunches, or a simple bowl with hearty buttered bread and grated Parmesan.
Why You’ll Love This Recipe
Roasting is the flavor key: oven-roasted fresh tomatoes and onions add caramelized sweetness and depth you don’t get from canned tomatoes alone. A high-powered blender and a little simmer deliver a smooth, restaurant-style finish that still feels homey.
For a complete, cozy meal, serve the soup with a warm panini like Heart-Healthy Turkey, Spinach & Balsamic Panini or a slab of buttered bread.
Ingredients You’ll Need
How to Make Tomato Basil Soup
- Preheat the oven to 400°F. Halve the ripe tomatoes lengthwise and arrange them cut-side up on a large (15×21-inch) sheet pan or divide between two smaller sheet pans. Quarter the yellow onions and scatter them among the tomatoes.
- Prepare the garlic for roasting: peel the outer layers of the garlic bulb while leaving individual clove skins intact, cut off about 1/4 inch from the top of the bulb to expose the cloves, drizzle the exposed cloves with 2 teaspoons olive oil, wrap the bulb tightly in foil, and place it on the sheet pan with the tomatoes and onions.
- Drizzle 1/4 cup olive oil over the tomatoes and onions, then sprinkle 1 teaspoon salt and 1/2 teaspoon pepper over everything. Toss gently to coat and spread in a single layer so the vegetables roast, not steam.
- Roast the tomatoes, onions, and garlic at 400°F for 40–45 minutes, until the tomatoes and onions are tender and slightly caramelized at the edges.
- While the vegetables roast, heat 2 tablespoons unsalted butter and 2 tablespoons olive oil in a large stockpot or cast-iron pot over medium heat until the butter melts. Add the (28-ounce) can whole tomatoes (undrained) and 2 tablespoons tomato paste, stirring for 2–3 minutes to marry the flavors.
- Stir in the (32-ounce) carton chicken stock, 1 teaspoon dried oregano, 1/4 teaspoon red pepper flakes if using, 1 to 2 teaspoons fresh thyme leaves (or 1/2 teaspoon dried), and 3-1/2 cups fresh basil leaves. Then add the roasted tomatoes and quartered onions to the pot along with any juices on the pan.
- Let the roasted garlic cool slightly, then squeeze 6–9 cloves from their skins into the pot (use more or fewer cloves depending on how garlicky you like it). Season the mixture with 2 teaspoons salt and 1 teaspoon pepper, then taste and adjust as you go.
- Bring the pot to a boil, then reduce the heat to low and simmer uncovered for 40 minutes, stirring every 5–10 minutes so nothing sticks and the flavors concentrate.
- Working in 3–4 batches, transfer the soup to a high-powered blender and blend until completely smooth—hold the lid with a towel and vent the blender slightly to avoid steam buildup. Return the blended soup to the pot.
- Taste and adjust seasonings as needed. If the soup tastes too acidic, stir in a teaspoon of granulated sugar to balance the flavor. Keep warm, then ladle into bowls and top with freshly grated Parmesan and hearty buttered bread, if desired.

Roast for Deep Flavor
Roasting at 400°F for 40–45 minutes is the single most important step for depth of flavor. The high oven heat caramelizes sugars in the tomatoes and onions, turning ordinary tomato soup into something richer and more complex.
Roast the garlic in foil on the same pan so it softens and sweetens—you’ll squeeze the softened cloves into the soup after roasting.
- Use a large (15×21-inch) sheet pan or two smaller pans so pieces are in a single layer.
- Toss tomatoes and onions with 1/4 cup olive oil, 1 teaspoon salt, and 1/2 teaspoon pepper before roasting.
- Prepare the garlic by cutting 1/4 inch from the top, drizzling 2 teaspoons olive oil, and wrapping in foil; squeeze out 6–9 cloves after roasting.
Blend Until Silky
A high-powered blender is the tool that gives this soup its restaurant-style velvet finish. Blend the hot soup in 3–4 batches so each batch empties easily and you avoid overfilling the blender.
Return all blended batches to the pot and taste for final seasoning—blending will mellow flavors, so final adjustments are normal.
- Vent the blender lid slightly and cover with a towel to release steam safely while blending hot liquid.
- Blend each batch until perfectly smooth to remove skins and any fibrous bits.
- Remember the basil tip: pack the leaves when measuring 3-1/2 cups so the soup gets the correct herbal lift.
Tame Tomato Acidity
Tomatoes vary in acidity depending on ripeness and variety. This recipe gives you two tools: roasting concentrates sweetness, and a teaspoon of granulated sugar will balance any lingering sharpness after blending.
Always taste after blending and after the 40-minute simmer—add salt, pepper, or sugar in small increments and re-taste until the soup is balanced.
- If tasting too acidic, stir in 1 teaspoon granulated sugar and re-taste.
- Adjust salt in small amounts—salt brings out sweetness and rounds flavors.
- A splash of cream or a pat of butter can mellow acidity if you want a richer finish (optional).
Tips for Success
Pack the basil: When measuring 3-1/2 cups of basil, pack the leaves into the cup—basil compresses and will wilt considerably when blended, so packed measurement ensures the right herb level.
Blend in batches: Use a high-powered blender and work in 3–4 batches for the silkiest texture; vent the lid slightly and drape a towel over it to release steam safely.
Quick weeknight shortcut: Skip the fresh tomatoes when short on time—use the canned whole tomatoes and tomato paste, but still roast the onions and garlic for that caramelized depth.
Fix bright acidity: If the finished soup tastes too sharp, stir in 1 teaspoon granulated sugar, then re-taste and adjust salt and pepper to balance.
Make-ahead & freeze: Cool completely, refrigerate up to 3 days, or freeze in airtight containers up to 3 months. Reheat gently on the stovetop over low heat to prevent scorching.
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Final Thoughts
This roasted tomato basil soup is a make-ahead winner—it improves after a day in the fridge and freezes well. Keep a container in the freezer for quick, comforting meals.
Serve bowls with grated Parmesan and hearty buttered bread, or pair with warm sandwiches for a complete meal.

Tomato Basil Soup Recipe
Equipment
- Large sheet pan (15″ x 21″”)or two smaller sheet pans
Ingredients
- 3 pounds ripe tomatoes I prefer campari/cocktail
- 2 large yellow onions
- 1 head garlic
- 6 tablespoons + teaspoons olive oil divided
- Salt and pepper
- 2 tablespoons unsalted butter
- 1 (28-ounce) can whole tomatoes undrained (I love Cento San Marzano)
- 2 tablespoons tomato paste
- 3-1/2 cups fresh basil leaves packed when measured, see note 1
- 1 to 2 teaspoons fresh thyme leaves or 1/2 teaspoon dried thyme
- 1 (32-ounce) carton chicken stock I prefer Swanson’s
- 1 teaspoon dried oregano
- 1/4 teaspoon red pepper flakes optional
- Hearty buttered bread optional
- Parmesan cheese optional
Instructions
- Preheat oven to 400°F. Halve the tomatoes lengthwise and arrange them on a large (15×21-inch) sheet pan or two smaller sheet pans; quarter the yellow onions and add them to the pan(s).
- Peel the outer layers of the garlic bulb while leaving individual clove skins intact. Cut off 1/4 inch from the top of the bulb, drizzle with 2 teaspoons olive oil, wrap tightly in foil, and place the garlic on the sheet pan with the tomatoes and onions.
- Drizzle 1/4 cup olive oil over the tomatoes and onions, sprinkle with 1 teaspoon salt and 1/2 teaspoon pepper, toss to coat, spread in an even layer, and roast 40–45 minutes until the vegetables are tender and slightly caramelized.
- In a large stockpot or cast-iron pot, heat 2 tablespoons unsalted butter and 2 tablespoons olive oil over medium heat until the butter melts. Add the (28-ounce) can whole tomatoes (undrained) and 2 tablespoons tomato paste, stirring 2–3 minutes.
- Stir in the (32-ounce) carton chicken stock, 1 teaspoon dried oregano, 1/4 teaspoon red pepper flakes if using, 1 to 2 teaspoons fresh thyme leaves (or 1/2 teaspoon dried), and 3-1/2 cups fresh basil leaves. Add the roasted tomatoes and onions with all their juices.
- Let the roasted garlic cool slightly, then squeeze 6–9 cloves from their skins into the pot and season the soup with 2 teaspoons salt and 1 teaspoon pepper, adjusting to taste.
- Bring the mixture to a boil, then reduce heat to low and simmer uncovered for 40 minutes, stirring every 5–10 minutes.
- Working in 3–4 batches, transfer the soup to a high-powered blender and blend until smooth. Taste and adjust seasonings; if the tomatoes are too acidic, add a teaspoon of granulated sugar.
- Top bowls with freshly grated Parmesan cheese and serve with hearty buttered bread, if desired.
