Ingredients
Scale
- 4 boneless, skinless chicken breasts (about 1.5-2 lbs)
- Salt and black pepper
- 2 tablespoons olive oil
- 3 large yellow onions, thinly sliced
- 3 cloves garlic, minced
- 2 tablespoons butter
- 1 tablespoon fresh thyme leaves (or 1 teaspoon dried)
- 1 cup beef broth
- 1 tablespoon Worcestershire sauce
- 1 teaspoon Dijon mustard
- 1½ cups shredded Gruyère cheese (Swiss cheese works too)
- Fresh parsley for garnish (optional)
Instructions
- Preheat your oven to 375°F.
- Season both sides of the chicken breasts generously with salt and pepper.
- Heat the olive oil in a large oven-safe skillet over medium-high heat. Once hot, add the chicken breasts and sear for 3-4 minutes per side until golden brown. They don’t need to be cooked through yet. Remove the chicken from the skillet and set aside on a plate.
- Reduce the heat to medium and add the butter to the same skillet. Once melted, add the sliced onions and a pinch of salt.
- Cook the onions, stirring occasionally, for about 20-25 minutes until they’re deeply caramelized and golden brown. This step takes patience, but it’s where all the flavor comes from. If the onions start to stick, add a splash of broth to deglaze the pan.
- Add the minced garlic and thyme to the onions and cook for another minute until fragrant.
- Pour in the beef broth, Worcestershire sauce, and Dijon mustard. Stir everything together and let it simmer for 2-3 minutes.
- Nestle the seared chicken breasts back into the skillet, spooning some of the onions and sauce over the top.
- Sprinkle the shredded Gruyère cheese over each chicken breast.
- Transfer the skillet to the preheated oven and bake for 15-20 minutes, until the chicken reaches an internal temperature of 165°F and the cheese is melted and bubbly.
- Let the chicken rest for 5 minutes before serving. Garnish with fresh parsley if you’d like, and spoon extra onions and sauce over the top.
- Prep Time: 10 minutes
- Cook Time: 45 minutes