Slice the tomatoes in half. Drizzle 1 tablespoon of olive oil onto a baking sheet, then place the tomato halves on the baking sheet and scatter with the sliced garlic. Season with a pinch of salt and pepper. Roast for 15-20 minutes.
Meanwhile, heat a large pot over medium heat. Add the remaining olive oil and sauté the onion, celery, and carrots until softened, about 5 minutes.
Add the chicken stock, roasted tomatoes and garlic, diced tomatoes, smoked paprika, oregano, salt, and pepper. Simmer for 20 minutes.
Remove from heat and add the basil leaves. Use an immersion blender to blend the soup until smooth.