French Onion Soup Chicken Skillet with Melted Gruyère Step-by-step instructions

Before you start

Before you start, make sure you have all the ingredients ready. Slice the onions thinly and evenly so they cook at the same rate. Pick the thyme leaves and chop them. Shred the Gruyère cheese if you bought a block.

Season the chicken breasts with black pepper. Have the butter, sherry, and beef broth measured and within reach. Preheat your oven’s broiler before you begin the final step.

Instructions

Caramelize the Onions

1. 1Prep the ingredients
   Thinly slice the yellow onions into half-moons. Pick the thyme leaves from the stems and chop them lightly. Season the chicken breasts on both sides with black pepper. Shred the Gruyère cheese if not already shredded.
   Look for Onions are thin and even, chicken is peppered, cheese is shredded.
   Tip Chilling the chicken before slicing helps if you want to butterfly the breasts for even thickness.
2. 2Caramelize the onions
   Heat a large cast-iron skillet over medium heat. Add the butter and let it melt. Add the sliced onions and thyme. Cook, stirring occasionally, until the onions are deeply golden and jammy, about 20 minutes. If they start to stick, add a splash of water.
   Look for Onions are soft, translucent, and turning deep brown with sweet aroma.
   Tip Do not rush this step; low and slow is key for rich caramelization.
3. 3Deglaze with sherry
   Pour the dry sherry into the skillet with the caramelized onions. Stir and scrape up any browned bits from the bottom of the pan. Let the sherry cook down for 1-2 minutes until mostly evaporated.
   Look for The sherry sizzles and reduces, leaving a glossy coating on the onions.
   Tip Use a wooden spoon to scrape the bottom well for maximum flavor.

The onions should be soft, deeply golden, and sweet-smelling. They will have reduced significantly in volume. The butter and thyme will have infused them with aroma.

The pan might have some browned bits at the bottom, which is good — those will be deglazed with sherry. Do not rush this step; it is the foundation of the dish’s flavor.

Sear and Braise the Chicken

4. 4Sear the chicken
   Push the onions to one side of the skillet. Increase the heat to medium-high. Place the seasoned chicken breasts in the skillet and sear for 3-4 minutes per side, until golden brown on both sides. The chicken will not be cooked through yet.
   Look for Chicken is golden-brown on both sides, with some caramelized bits sticking.
   Tip Do not overcrowd; sear in batches if necessary.
5. 5Braise in broth
   Pour the beef bone broth into the skillet. Nestle the chicken breasts among the onions. Bring the liquid to a simmer, then reduce the heat to low. Cover and cook for 10-12 minutes, until the chicken is cooked through and registers 165°F (74°C) in the thickest part.
   Look for The broth is simmering gently and the chicken is nearly cooked through.
   Safe temperature 165°F (74°C) internal temperature (poultry)
   Tip Use an instant-read thermometer to check the thickest part of the breast.
6. 6Top with Gruyère
   Preheat the broiler. Sprinkle the shredded Gruyère evenly over the chicken and onions. Transfer the skillet to the broiler and broil for 2-3 minutes, until the cheese is melted and blistered in spots.
   Look for The cheese is bubbly, golden-brown, and slightly blistered.
   Tip Watch closely to avoid burning; broilers vary in intensity.

The chicken breasts should be golden-brown on both sides and nearly cooked through after braising. The broth will be simmering and slightly reduced, with the onions distributed around the chicken. The kitchen will smell rich and savory. The chicken should register at least 165°F (74°C) before adding the cheese.

Broil the Gruyère

7. 7Rest and serve
   Remove the skillet from the broiler and let it rest for 5 minutes. The cheese will set slightly. Serve the chicken with the caramelized onion broth spooned over the top.
   Look for The cheese is melted and the broth is bubbling around the edges.
   Tip Letting it rest helps the juices redistribute in the chicken.

The cheese should be fully melted and bubbly, with dark blistered spots. The edges of the cheese may be lightly charred, which adds a smoky flavor. The broth underneath will be bubbling. The cheese should be golden brown, not burnt. Let the skillet rest for a few minutes before serving.

Common mistakes

A common mistake is rushing the caramelization of the onions. If the heat is too high, they will burn instead of becoming sweet and jammy. Another pitfall is overcooking the chicken, which makes it dry.

Use a thermometer to check for doneness. Also, do not skip the sherry deglazing step — it lifts the browned bits and adds essential flavor. Finally, watch the broiler closely so the cheese doesn’t burn.

How to tell it’s done

The dish is done when the chicken is cooked through to an internal temperature of 165°F (74°C) in the thickest part, and the cheese is melted and blistered under the broiler.

The onions should be deeply caramelized and the broth should have reduced slightly to a saucy consistency. The cheese should be golden brown with dark spots, and the edges of the skillet will be bubbling.

• Poultry: 165°F (74°C) in the thickest part