Ingredients:
4 boneless, skinless chicken breasts
Salt and pepper to taste
2 tablespoons olive oil
2 large onions, thinly sliced
2 cloves garlic, minced
1 cup sliced mushrooms
1 tablespoon all-purpose flour
1 cup beef broth
1 tablespoon Worcestershire sauce
1 teaspoon dried thyme
1 cup shredded Gruyere cheese
Instructions:
Preheat oven to 375°F (190°C).
Season chicken breasts with salt and pepper.
In a large skillet, heat olive oil over medium-high heat. Add chicken breasts and cook until golden brown on both sides, about 4-5 minutes per side. Remove chicken from skillet and set aside.
In the same skillet, add onions and garlic. Cook until onions are caramelized, about 10-12 minutes.
Add sliced mushrooms to the skillet and cook until they release their juices, about 4-5 minutes.
Sprinkle flour over the onion and mushroom mixture, stirring to combine.
Slowly pour in beef broth and Worcestershire sauce, stirring constantly until the mixture thickens, about 3-4 minutes.
Stir in dried thyme.
Return chicken breasts to the skillet, spooning the onion and mushroom mixture over the top. Sprinkle shredded Gruyere cheese over the chicken.
Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until chicken is cooked through and cheese is melted and bubbly.
Serve hot, garnished with fresh thyme if desired.