01 - Bring a large pot of salted water to a boil. Prepare pasta following package directions until al dente. Drain thoroughly and reserve 1/2 cup of pasta water.
02 - Butterfly chicken breasts. Season both sides with salt, pepper, and dried Italian herbs if using.
03 - Heat olive oil in a large skillet over medium-high heat. Sear chicken on each side until golden and fully cooked, approximately 5 to 6 minutes per side. Transfer chicken to a plate and cover loosely to rest.
04 - In the same skillet over medium heat, melt butter. Add onion and sauté until softened, 2 to 3 minutes. Stir in minced garlic and cook until fragrant, about 1 minute.
05 - Deglaze skillet with chicken broth, scraping up browned bits from the pan.
06 - Add heavy cream to skillet and bring to a gentle simmer. Whisk in Parmesan cheese until the sauce is smooth. Adjust seasoning with salt and pepper as needed.
07 - Slice rested chicken into thin strips. Return chicken to the skillet along with cooked pasta. Toss everything together, adding reserved pasta water a little at a time until desired sauce consistency is reached.
08 - Stir in chopped parsley. Serve immediately, garnished with extra parsley and Parmesan cheese as desired.