01 - Pat chicken breasts dry and season both sides with salt and black pepper.
02 - Warm olive oil and butter in a large skillet over medium-high heat.
03 - Cook chicken breasts 5 to 6 minutes per side until golden brown and cooked through. Transfer to a plate and cover loosely with foil.
04 - Add chopped onion to the same skillet and cook for 2 minutes until softened.
05 - Stir in minced garlic and thyme, cooking for 1 minute until fragrant.
06 - Pour in chicken broth and lemon juice, scraping the skillet bottom to release browned bits.
07 - Reduce heat to medium and let the sauce simmer for 2 to 3 minutes until slightly thickened.
08 - Return chicken breasts to skillet, spoon sauce over them, and cook for an additional 2 minutes to reheat thoroughly.
09 - Sprinkle chopped parsley over chicken before serving.