01 - Pat chicken breasts dry with paper towels and season both sides generously with salt and pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Add chicken breasts and sear for 3-4 minutes per side until golden brown and cooked through. Transfer to a plate and cover loosely with aluminum foil to rest.
03 - Reduce heat to medium. Add butter to the same skillet and add sliced mushrooms. Sauté for 5-6 minutes, stirring occasionally, until mushrooms are browned and their liquid has evaporated.
04 - Add minced garlic to the skillet and cook for 1 minute until fragrant, being careful not to burn it.
05 - Pour in heavy cream, chicken broth, and Dijon mustard. Add thyme and oregano. Stir to combine and bring to a gentle simmer. Cook for 3-4 minutes, stirring occasionally, until sauce thickens slightly.
06 - Return chicken to the skillet, nestling pieces into the sauce. Simmer for 2-3 minutes until chicken is heated through and coated with sauce. Stir in chopped parsley and adjust seasoning with additional salt and pepper if needed.
07 - Plate chicken breasts topped with mushrooms and sauce. Garnish with extra fresh parsley if desired.