If you’re a fan of French onion soup, you’re going to love this twist. These French Onion Chicken breasts are packed full of sweet, jammy caramelised onions and gooey melted cheese, all tucked inside juicy chicken and baked until golden and bubbling. The onions bring loads of rich flavour, and the cheese turns wonderfully melty and comforting. Best of all, it’s a lot easier to make than it looks – simple ingredients, a bit of hands-on time at the start, and then the oven does the rest. It’s the kind of meal that feels special enough for a weekend but is straightforward enough to pull together on a weeknight too. Serve it up with some greens, a bit of mash, or even crusty bread to mop up the delicious pan juices.
For another easy, flavour-packed chicken dish, check out Crispy Chicken in Creamy Cavolo Nero Sauce.
🍴 Tools You’ll Need
Sharp Chefs Knife – Like this one for thin onion slices and carefully slicing the chicken.
Silicone Tongs — Like these helps turn the chicken safely without losing the filling.
Baking Dish – Holds everything while it bakes, I use this one which makes for easy cleaning.
Cheese Grater – Freshly grated cheese melts best, this grater is perfect for the job.

French Onion Stuffed Chicken
Ingredients
- 2 tablespoons unsalted butter
- 4 large onions halved and thinly sliced
- Pinch of salt and pepper to season
- 2 teaspoons fresh chopped thyme divided
- 2 tablespoons white wine sherry or balsamic vinegar, optional
- 2 cloves garlic minced
- 0.5 cup beef broth or stock divided
- 1 tablespoon olive oil
- 4 boneless skinless chicken breasts
- 2 teaspoons garlic powder
- 1 teaspoon ground thyme
- 1 cup shredded gruyere cheese or mozzarella cheese
- 4 tablespoons freshly grated parmesan cheese
Instructions
- Get your oven on at 200°C (400°F) and lightly grease a 9×12-inch baking dish. Set that aside for later.
- Melt the butter in a large frying pan over medium-high heat. Add the sliced onions, season with salt, pepper, and half the chopped thyme. Cook for 5–8 minutes until they start to soften. Turn the heat down to medium and keep cooking, stirring every so often, until the onions are soft, golden, and jammy (about 15 minutes). If the pan starts to dry out, splash in a bit of the beef broth to stop them sticking.
- If you fancy a bit of extra flavour, pour in the white wine, sherry, or balsamic vinegar. Let it bubble for a minute until it thickens slightly.
- Stir in the minced garlic and cook for about a minute until it smells amazing. Then take the pan off the heat and let the onions cool slightly.
- Carefully cut a pocket into each chicken breast (slice it in half horizontally without going all the way through), a good sharp knife like this is key for slicing the onions thinly and cutting neat pockets. Season the chicken all over—including inside the pockets—with salt, pepper, garlic powder, and ground thyme.
- Spoon 1–2 tablespoons of the caramelised onions into each pocket, then stuff them with the shredded Gruyère (or mozzarella) and a bit of Parmesan. Seal each breast with toothpicks to hold everything in place.
- Tip the rest of the caramelised onions into your prepared baking dish and stir in the remaining beef broth. Set aside for now.
- Heat the olive oil in the same frying pan over medium-high heat. Sear the stuffed chicken for about 4 minutes on each side until golden—don’t worry, it won’t be fully cooked yet. Flip the chicken easily with a sturdy set of tongs like these to keep the filling secure.
- Lay the browned chicken breasts on top of the onions in the baking dish, I bake everything in a sturdy dish like this, it holds the juices nicely and makes cleanup easy. Spoon a bit of the oniony sauce over each one and sprinkle with the remaining chopped thyme. Bake for 15–20 minutes, until the chicken is cooked through and the cheese is lovely and melty.
- Take out the toothpicks and serve the chicken with the caramelised onions and pan juices spooned over the top. Perfect with a side of greens or mash!
Top Tips for this Stuffed French Onion Chicken
Caramelise properly: Don’t rush the onions—low and slow gives you the best deep, sweet flavour.
Keep it juicy: Let the chicken rest for a few minutes after baking to keep it tender and juicy.
Wine boost: Deglazing with white wine or sherry adds a lovely extra depth to the onions—totally worth it if you have a splash handy.
One-pan tip: If your frying pan is ovenproof, you can bake everything in the same pan—less washing up!