01 - Season chicken breasts with salt and pepper. Lightly dredge in flour, shaking off excess.
02 - Heat olive oil in a large skillet over medium-high heat. Sear chicken breasts for 4–5 minutes per side, until golden and just cooked through. Transfer to a plate and cover loosely with foil.
03 - In the same skillet, add mushrooms and onion. Sauté for 4 minutes until softened. Add garlic and cook 1 minute more.
04 - Pour in chicken broth, scraping up any browned bits from the pan. Stir in heavy cream, Dijon mustard, thyme, and rosemary. Bring to a gentle simmer.
05 - Return chicken breasts to the skillet, nestling them into the sauce. Simmer for 5–7 minutes until sauce thickens and chicken is heated through.
06 - Stir in fresh parsley and adjust seasoning to taste. Serve chicken with plenty of sauce, garnished with extra parsley if desired.