Heat olive oil in a large skillet over medium heat, about 350°F. Add the sliced chicken sausage. Cook until browned on both sides, about 5 minutes. Remove from skillet and set aside.
In the same skillet, add diced chicken breasts. Cook for 5–7 minutes or until chicken is no longer pink in the center and remove from skillet and set aside.
While the chicken cooks, bring a pot of salted water to a boil. Add pasta and cook according to package instructions. Drain and set aside.
Add onion, garlic, and sprinkle in Italian seasoning, salt, and pepper and cook until translucent. Pour in the chicken broth and heavy cream. Stir well, scraping the bottom to release any browned bits. Bring the mixture to a simmer.
Turn off heat and stir in the shredded Pepper Jack and grated Parmesan. Continue stirring until the cheese is fully melted and the sauce becomes smooth and creamy.
Add the drained pasta and meat to the skillet. Toss everything together until well coated in the creamy sauce. Let it sit for 2 minutes off the heat to thicken slightly. Garnish with chopped parsley before serving.
