01 - Season the chicken pieces with salt, pepper, and Italian seasoning, coating evenly.
02 - Heat olive oil and butter in a large, deep skillet over medium-high heat. Add chicken and cook until lightly browned and cooked through, about 5-6 minutes. Remove chicken from pan and set aside.
03 - Add onion to the same pan and sauté for 2-3 minutes until softened. Add garlic and cook for 30 seconds until fragrant.
04 - Stir in the red bell pepper and cook for another 2 minutes until slightly softened.
05 - Add uncooked pasta to the pan, followed by chicken broth and heavy cream. Stir to combine, scraping any browned bits from the bottom of the pan.
06 - Bring to a gentle simmer. Cover and 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 stir in Parmesan cheese. Cook for 2-3 minutes until spinach wilts and sauce thickens.
08 - Taste and adjust seasoning if needed. Serve hot, garnished with chopped parsley and extra Parmesan if desired.