1-First, get your ingredients ready and preheat the oven to 400 degrees Fahrenheit. Line a baking sheet and arrange the halved tomatoes and peeled garlic cloves on it; drizzle with 3 tablespoons of olive oil and season with salt and freshly ground black pepper to taste. Slide the baking sheet into the oven and roast for 40 to 45 minutes, until the tomatoes are soft and caramelized. This step builds the base flavor for your roasted tomato basil soup.

2-While the tomatoes roast, heat 0.5 tablespoon of olive oil in a pan over medium heat and add the 2 thinly sliced yellow onions. Cook them until they turn golden and sweet, which takes about 20 minutes that’s the caramelizing process. Once done, set them aside to cool a bit. This part adds a delicious depth to the soup without much effort.

3-After roasting, let the tomatoes and garlic cool for 10 minutes. Then, blend them until smooth using a food processor, blender, or immersion blender. Add the 0.5 cup packed fresh basil leaves, the caramelized onions, and 0.5 teaspoon dried oregano, then blend again for a creamy texture. This method ensures your roasted tomato basil soup has that fresh, vibrant taste.

4-Next, transfer the mixture to a pot and heat it over medium-low. Stir in 1 to 2 cups of water or vegetable broth to get the thickness you like. Taste and adjust salt and pepper, and mix in any optional add-ins like coconut milk, dairy milk, cream, cheese, or butter for extra creaminess. Let it simmer for about 10 minutes, stirring occasionally.