Quick Recipe Version (TL;DR)
Quick Ingredients
- 3 lb Roma tomatoes, halved
- 1 medium yellow onion, sliced; 6 garlic cloves
- 4 tbsp extra-virgin olive oil (divided)
- 1/2 tsp kosher salt; 1/2 tsp black pepper; 1/4 tsp red pepper flakes (optional)
- 2 tbsp tomato paste
- 2 to 2 1/2 cups low-sodium vegetable broth
- 1 tsp sugar (optional), 1 cup packed basil leaves
- 1 tbsp balsamic vinegar; 1/3 cup heavy cream
- 8 slices sourdough; 8 oz sharp cheddar, shredded
- 4 tbsp unsalted butter; 1 tbsp mayonnaise (optional)
- Extra basil, cream, and black pepper for garnish
Do This
- 1. Heat oven to 425°F (220°C). Roast tomatoes, onion, and garlic with 3 tbsp oil, salt, and pepper for 30 minutes, cut sides up.
- 2. In a pot, warm 1 tbsp oil. Cook tomato paste 1 minute, add red pepper flakes, roasted veg and juices, 2 cups broth, and sugar; simmer 10 minutes.
- 3. Add basil and vinegar. Blend smooth; thin with up to 1/2 cup more broth if needed. Stir in cream and adjust seasoning.
- 4. Butter the outsides of the bread (mix in mayo if using). Fill with cheddar to make 4 sandwiches.
- 5. Griddle over medium-low 3–4 minutes per side until deep golden and melty; rest 1 minute.
- 6. Cut sandwiches into triangles for dippers.
- 7. Ladle soup into bowls, garnish with basil and a cream swirl, and dunk away.
Why You’ll Love This Recipe
- Roasting concentrates the tomatoes, giving the soup deep, sweet-savory flavor.
- Silky, basil-forward soup finished with a gentle cream swirl for restaurant-level elegance.
- Golden, crispy cheddar-on-sourdough triangles made for dunking.
- Simple techniques and easy prep for a cozy weeknight dinner.
Grocery List
- Produce: Roma tomatoes (3 lb), yellow onion, garlic, fresh basil
- Dairy: Sharp cheddar (8 oz), heavy cream, unsalted butter, optional mayonnaise
- Pantry: Sourdough bread, extra-virgin olive oil, tomato paste, low-sodium vegetable broth, balsamic vinegar, kosher salt, black pepper, red pepper flakes, sugar (optional)
Full Ingredients
For the Roasted Tomato–Basil Soup
- 3 lb ripe Roma (plum) tomatoes, halved lengthwise
- 1 medium yellow onion, thickly sliced (about 1 cup)
- 6 large garlic cloves, peeled
- 3 tbsp extra-virgin olive oil (for roasting)
- 1 tbsp extra-virgin olive oil (for soup base)
- 1/2 tsp kosher salt, plus more to taste
- 1/2 tsp freshly ground black pepper
- 1/4 tsp red pepper flakes (optional)
- 2 tbsp tomato paste
- 2 cups low-sodium vegetable broth, plus up to 1/2 cup more to thin if needed
- 1 tsp granulated sugar (optional, to balance acidity)
- 1 cup packed fresh basil leaves, plus extra for garnish
- 1 tbsp balsamic vinegar (or sherry vinegar)
- 1/3 cup heavy cream (or half-and-half)
For the Grilled Cheese Dippers
- 8 slices sourdough bread (1/2-inch thick)
- 8 oz sharp cheddar cheese, coarsely shredded (about 2 cups packed)
- 4 tbsp unsalted butter, softened
- 1 tbsp mayonnaise (optional, for extra crispness)
Optional Garnishes
- Fresh basil leaves, torn
- Extra heavy cream, for swirling
- Freshly cracked black pepper
- Drizzle of extra-virgin olive oil
Step-by-Step Instructions
Step 1: Roast the tomatoes, onion, and garlic
Preheat the oven to 425°F (220°C). Arrange the tomatoes (cut sides up), onion, and garlic on a large rimmed baking sheet. Drizzle with 3 tablespoons olive oil and season with 1/2 teaspoon kosher salt and 1/2 teaspoon black pepper. Roast for 30 minutes, until the tomatoes look slightly blistered and the edges of the onions are caramelized. Do not discard the flavorful juices on the pan.
Step 2: Build and simmer the soup base
Heat a large pot over medium heat and add the remaining 1 tablespoon olive oil. Stir in the tomato paste and cook for 60 seconds to caramelize it slightly. Add the red pepper flakes (if using), then scrape in the roasted tomatoes, onion, garlic, and all the pan juices. Pour in 2 cups vegetable broth and add the sugar if your tomatoes are very tangy. Bring to a gentle simmer and cook for 10 minutes to meld the flavors.
Step 3: Blend silky smooth with basil and vinegar
Remove the pot from heat. Add the basil leaves and balsamic vinegar. Blend the soup until completely smooth using an immersion blender. Alternatively, carefully blend in batches in a stand blender, venting the lid to release steam. If the soup seems too thick, thin with up to 1/2 cup additional warm broth or water.
Step 4: Finish with cream and season to taste
Return the pot to low heat and stir in the heavy cream. Taste and adjust seasoning with more salt and pepper as needed. Keep warm while you make the grilled cheese.
Step 5: Assemble the grilled cheese sandwiches
In a small bowl, mix the softened butter with the mayonnaise (if using) for easy spreading. Lay out 4 slices of sourdough and evenly mound the shredded cheddar on top. Cap with the remaining bread. Spread the butter mixture thinly over the outsides of each sandwich.
Step 6: Griddle to golden and cut into dippers
Heat a large skillet or griddle over medium to medium-low heat. Cook the sandwiches for 3–4 minutes per side, pressing lightly, until the bread is deep golden and the cheese is fully melted. Transfer to a wire rack for 1 minute to stay crisp, then cut each sandwich into 2–3 triangles for dunkable dippers.
Step 7: Serve and garnish
Ladle the soup into warm bowls. Garnish with a small swirl of cream, a few torn basil leaves, a crack of black pepper, and a light drizzle of olive oil if you like. Serve immediately with the grilled cheese triangles for dunking.
Pro Tips
- Roast cut sides up to concentrate tomato juices and avoid sogginess.
- Scrape every bit of fond and juice from the sheet pan into the pot for maximum flavor.
- Blooming tomato paste in oil adds body and a slow-simmered taste in minutes.
- For ultra-smooth soup, blend a full minute after it looks smooth and strain if desired.
- Keep grilled cheese crisp by resting on a wire rack, not a plate, before slicing.
Variations
- Roasted Red Pepper Twist: Add 1 roasted red bell pepper and 1/2 tsp smoked paprika to the blender for a sweeter, smoky soup.
- Cheese Swap: Use a 50/50 mix of sharp cheddar and fontina or Gruyère for extra stretch and nutty flavor.
- Dairy-Free: Finish the soup with 1/3 cup unsweetened coconut milk or cashew cream and use plant-based butter and cheese for the dippers.
Storage & Make-Ahead
Soup keeps well: refrigerate in an airtight container up to 4 days or freeze up to 3 months. Reheat gently over low heat, adding a splash of broth if it thickens. Stir in fresh basil or a touch more cream after reheating for brightness. Grilled cheese is best fresh; however, you can keep finished sandwiches warm on a wire rack set over a sheet pan in a 200°F (95°C) oven for up to 45 minutes. To prep ahead, assemble sandwiches up to 24 hours in advance, wrap, and refrigerate; griddle just before serving. Re-crisp leftovers in a skillet or 350°F (175°C) toaster oven for 5–7 minutes. Freezing grilled cheese is not recommended.
Nutrition (per serving)
Approximate values for 1 bowl of soup plus 2 grilled cheese triangles: 830 calories; 30 g protein; 66 g carbohydrates; 49 g fat; 7 g fiber; 1,200 mg sodium. Actual values will vary based on brands and exact portions.
