Season the chicken breasts with kosher salt, black pepper, Italian seasoning, and paprika. Rub the spices evenly over both sides.
In a large pot or Dutch oven, heat the olive oil over medium heat. Add the diced onion and sauté for 2-3 minutes until translucent. Add minced garlic and cook for 1 more minute until fragrant.
Add the seasoned chicken breasts to the pot and cook for 4-5 minutes on each side until browned but not fully cooked through. Remove chicken and set aside.
Add the chopped carrots to the pot and stir for about 2 minutes to release flavors.
Add the long-grain white rice to the pot, stirring to coat in oil and mix with vegetables. Cook for 1-2 minutes to lightly toast the rice.
Pour in the chicken broth and bring to a gentle boil. Place the chicken breasts back into the pot, ensuring they are submerged.
Reduce heat to low, cover, and simmer for about 20 minutes until rice is tender and chicken is cooked through.
Mix cornstarch with whole milk or half and half until smooth. Stir into the pot with grated Parmesan cheese. Cook for 2-3 minutes until sauce thickens.
Fluff the rice with a fork, slice the chicken, and serve garnished with fresh parsley.