Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Halve the Roma tomatoes and the yellow onion, then place them on the baking sheet along with the peeled garlic cloves.
Drizzle the vegetables with extra virgin olive oil and season with sea salt and black pepper.
Roast the vegetables for 35 to 40 minutes until the tomatoes are blistered and the onions are caramelized.
While the vegetables roast, poach the chicken breast in simmering water for 12 to 15 minutes until cooked through, then shred with two forks.
Transfer the roasted tomatoes, onion, and garlic into a high-speed blender, ensuring you include all the flavorful juices from the pan.
Add the vegetable broth and fresh basil to the blender and process until the soup reaches a velvety, smooth consistency.
Pour the soup into a pot over medium heat, stir in the shredded chicken, and simmer for 5 minutes to meld the flavors.
Ladle the soup into bowls and garnish with the grated parmesan cheese before serving.