01 - Combine chicken pieces with salt, pepper, and Italian seasoning in a bowl, tossing evenly to coat.
02 - Heat olive oil and butter in a large deep skillet over medium-high heat. Add seasoned chicken and cook for 5-6 minutes until lightly browned and cooked through. Transfer chicken to a plate and set aside.
03 - Add chopped onion to the same pan and sauté for 2-3 minutes until softened and translucent. Add minced garlic and cook for 30 seconds until fragrant.
04 - Stir in diced red bell pepper and continue cooking for 2 minutes until slightly tender.
05 - Add uncooked pasta to the pan, then pour in chicken broth and heavy cream. Stir well to combine, scraping up any browned bits from the bottom of the pan.
06 - Bring mixture to a gentle simmer, then cover and reduce heat to medium-low. Cook for 10-12 minutes, stirring occasionally, until pasta is al dente and most liquid is absorbed.
07 - Return cooked chicken to the pan. Add baby spinach and Parmesan cheese, stirring until spinach wilts and sauce thickens, about 2-3 minutes. Taste and adjust seasoning as needed.
08 - Divide pasta among bowls and garnish with chopped fresh parsley and additional Parmesan cheese if desired. Serve immediately.