01 - Season the chicken breasts on both sides with salt and black pepper.
02 - Heat the olive oil in a large skillet over medium-high heat. Add the chicken and cook 5-6 minutes per side, until golden and cooked through. Remove from skillet and set aside.
03 - In the same skillet, reduce heat to medium, add butter, then sauté onions and garlic until fragrant, about 2 minutes. Add the sliced mushrooms and cook until softened and browned, about 5 minutes.
04 - Pour in the chicken broth, scraping up any browned bits from the bottom. Let simmer for 2 minutes.
05 - Add the heavy cream and thyme; stir to combine. Simmer for another 2-3 minutes, until the sauce thickens slightly.
06 - Return the chicken to the skillet. Spoon sauce and mushrooms over the chicken, simmer for 2-3 minutes, until heated through.
07 - Sprinkle with fresh parsley and serve hot.