French onion chicken combines the classic elements of French onion soup—caramelized onions, melted cheese, and savory broth—with tender, juicy chicken breasts.
Season the chicken breasts with salt and pepper. Heat a large oven-safe skillet over medium-high heat and add the olive oil. Sear the chicken breasts on both sides until golden brown, about 3-4 minutes per side. Transfer the chicken to a plate and set it aside.
In the same skillet, melt the butter over medium heat. Add the thinly sliced onions and cook, stirring occasionally, until they become golden brown and caramelized, about 15-20 minutes. This slow cooking process allows the natural sugars in the onions to develop and adds depth of flavor.
Add the minced garlic, dried thyme, and dried rosemary to the skillet with the caramelized onions. Stir well to combine and cook for an additional minute until the herbs become fragrant.
Pour the broth into the skillet, scraping the bottom to release any browned bits (this adds flavor). Bring the mixture to a simmer and let it cook for a couple of minutes to allow the flavors to meld together.
Place the seared chicken breasts back into the skillet, nestling them into the onion mixture. Spoon some of the onions over the top of each chicken breast.
Transfer the skillet to the preheated oven and bake for approximately 20-25 minutes, or until the chicken reaches an internal temperature of 165F. The baking time may vary depending on the thickness of the chicken breasts.
Remove the skillet from the oven and sprinkle the shredded Swiss cheese over the chicken and onions. Return the skillet to the oven and broil for an additional 2-3 minutes, or until the cheese is melted and lightly browned.
Garnish with chopped fresh parsley, if desired, and serve the French onion chicken hot. This dish pairs wonderfully with mashed potatoes, rice, or crusty bread to soak up the flavorful onion sauce.