Heat the olive oil in a large pot over medium heat. Add the chicken and season with salt, pepper, paprika, and Italian seasoning. Cook for 1-2 minutes, just until lightly golden. Transfer the chicken to a plate and set aside.
Melt the butter in the same pot, then add the onion and cook for 2 minutes until softened. Stir in the mixed vegetables and cook for 1 minute. Add the garlic and cook for 30 seconds.
Add the rinsed rice, pour in the chicken stock, and stir, scraping up any browned bits from the bottom of the pan.
Return the chicken to the pot along with any juices and bring to a boil.
Cover with a tight-fitting lid, reduce the heat to low, and simmer for 15 minutes without lifting the lid. Remove from heat and let rest, covered, for 10 minutes.
Uncover, fluff with a fork, and gently stir in the parsley and Parmesan. Serve warm.