Cheesy French Onion Chicken with Gruyère

Ingredients:

• 4 boneless, skinless chicken breasts
• 2 tablespoons olive oil
• 1 1/2 teaspoons kosher salt, divided
• 1/4 teaspoon freshly ground black pepper
• 2 tablespoons unsalted butter
• 2 Vidalia onions, peeled and thinly sliced into half moons
• 3 cloves garlic, thinly sliced
• 1 bay leaf
• 1 tablespoon all-purpose flour
• 1/4 cup marsala wine
• 1/4 cup sherry vinegar
• 1 1/2 cups low-sodium chicken stock or beef broth
• 2 teaspoons Worcestershire sauce
• 2 teaspoons fresh thyme leaves, finely chopped, plus more for garnish
• 1-2 cups shredded Gruyère cheese (or Emmental cheese)
• Flaky sea salt, for serving
• Baguette or crusty bread, for serving

Optional additions:

• 1/4 cup chopped mushrooms
• 1/4 cup chopped spinach or kale
• 1/4 teaspoon red pepper flakes

Instructions:

1. Preheat oven: Preheat oven to 375°F (190°C).
2. Prep chicken: Pat chicken breasts dry with paper towels and season generously with 1 teaspoon kosher salt and 1/4 teaspoon black pepper.
3. Cook chicken: Heat olive oil in a large skillet over high heat. Add chicken breasts and cook undisturbed for 5-7 minutes, or until chicken releases easily from the pan. Flip and cook for another 4-5 minutes. Transfer chicken to a large plate.
4. Caramelize onions: Reduce heat to medium. Add butter to the pan. Add thinly sliced onions and stir well. Cover with a lid and cook for 10-15 minutes, stirring occasionally, or until onions have softened.
5. Add garlic: Remove lid, add thinly sliced garlic, 1/2 teaspoon kosher salt, and 1 bay leaf. Cook for an additional 10-15 minutes, until onions are caramelized.
6. Make sauce: Increase heat to medium-high. Add flour and stir until well absorbed (about 1 minute). Deglaze with marsala wine and sherry vinegar, scraping browned bits off the bottom of the pan. Stir in chicken broth, Worcestershire sauce, and chopped thyme leaves. Bring to a boil.
7. Finish and serve: Return chicken to the pan. Sprinkle with shredded Gruyère cheese (depending on how much cheese you like). Transfer to the oven and cook for 10-12 minutes, or until chicken's internal temperature registers 165°F. Optionally, broil for 1-2 minutes for a golden brown and bubbly finish. Garnish with fresh thyme and flaky sea salt. Serve immediately with crusty bread on the side.

Optional additions:

• For extra flavor: Add chopped mushrooms, spinach, kale, or red pepper flakes.
• For a richer texture: Use a combination of Gruyère and Parmesan cheese.
• For a spicier kick: Add a pinch of cayenne pepper to the sauce.

Enjoy your delicious Chicken with Caramelized Onions!