Preheat the oven to 375°F (190°C).
In a 9x9-inch glass baking dish, combine the uncooked rice, 1/2 cup of the parmesan, and 4 tablespoons of the pesto; spread evenly.
Place the chicken breasts on top of the rice mixture and season them with salt and pepper to taste.
Pour the chicken stock over the rice and chicken, then gently stir the rice under the chicken to level it.
Cover the dish tightly with foil and bake for 45 to 60 minutes, or until the rice is tender and the chicken is cooked through.
Carefully remove the chicken from the baking dish and shred it into large pieces using two forks.
Return the shredded chicken to the dish, add the heavy cream, the remaining 2 tablespoons pesto, and 3/4 of the diced tomatoes; stir gently to combine.
Portion into 4 servings and top each with the remaining diced tomatoes, the rest of the parmesan (if desired), and a sprinkle of Italian seasoning.
