Preheat the oven to 190°C (375F). Line a large baking sheet with parchment paper. Cut the roma tomatoes and the carrots in half, the onion in big chunks and keep the cherry tomatoes whole. Add it all to the baking sheet. Add whole cloves of garlic. Drizzle the olive oil and season with pepper and salt. Give it all a good toss so it's evenly oiled and seasoned. Bake the veggies in the oven for 1 hour. Check half way and if needed give it a toss to let it bake evenly.
Transfer the roasted veggies and its juices into a food processor. Blend until smooth. Depending on the size of your food processor, do it in two batches or all in one.
Transfer the smooth veggies into a dutch oven and heat up on medium heat. Add the vegetable broth and heat it up all the way for about 8 minutes. Add the balsamico vinegar, and chili flakes, give it a good stir.
Last step is to add a few spoons of homemade pesto. It will the soup a creamy texture. Serve with fresh bread!