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, black pepper, and dried oregano.
Roast the vegetables for 25 to 30 minutes until the tomatoes are blistered and the onions are tender.
While the vegetables roast, season the chicken breast with a pinch of salt and pepper, then sear in a pan over medium heat for 6-7 minutes per side until fully cooked.
Transfer the roasted tomatoes, onion, and garlic into a high-speed blender, ensuring you include any juices from the pan.
Add the chicken bone broth and half of the fresh basil to the blender, then process on high until the soup is completely smooth and creamy.
Slice the cooked chicken breast into thin strips or small cubes.
Pour the hot soup into a bowl, swirl in the plain Greek yogurt for extra creaminess, and top with the sliced chicken and the remaining fresh basil ribbons.