This dish is built on the same principles as a traditional French Onion Soup but with the addition of chicken. It’s half soup and half stew – the inclusion of chicken and a thicker sauce making it substantial enough for a main meal. This has fast become one of my favourite warming winter meals. It’s utterly delicious and comforting with just enough effort in the cooking to make it satisfying to prepare but not so arduous that you think twice about whipping it up. As with French onion soup, the careful cooking and caramelising of the onions is really important and is what binds the whole dish together, giving it that amazing rich brown colour that all good French Onion soups have. The differences are of course the inclusion of boneless skinless thigh fillets (breast fillets just wouldn’t be as good here) and the fact that it lacks the usual bread and cheese topping. Instead, just grated Gruyère cheese (and lots of it please) is placed on top of the finished dish and then grilled until beautifully melted and golden. Crusty bread served alongside is a must and I also like teaming it with a warm green bean salad dressed with lots of chopped tarragon and a thick dijon mustard vinaigrette. This is a must make knock out of a dish.
Ingredients – Serves 4-6 Adapted from The Kitchn
3 tablespoons butter
1 kg onions, sliced into thin half-moons
Salt and freshly ground black pepper
4 garlic cloves, sliced
2 small sprigs thyme, leaves only
1 sprig rosemary
2 cups best quality beef stock, divided
1 tablespoon balsamic vinegar
2 tablespoons Dijon mustard
1 tablespoon olive oil
1.5kg boneless skinless chicken thighs
1 cup finely grated Gruyère cheese
Melt the butter in a heavy bottomed sauté pan over medium heat. When the butter has melted completely and foams up, add the onions. Stir as you add the onions to coat them in the butter. Sprinkle lightly with salt and black pepper. Cook the onions for about 40 minutes over low heat, stirring occasionally.
When the onions have developed an evenly light beige color throughout, add the garlic, thyme leaves, and whole rosemary sprig, and cook for a few minutes more, stirring frequently. Turn the heat up to high and cook for a further 5 minutes, stirring frequently. You want dark, slightly burnt spots to appear on the onions, and for them to develop a rich mahogany color. When the onions get quite dark, add 1 cup of the beef stock. Add it slowly, stirring and scraping the pan vigorously to scrape up any burnt or stuck-on bits. When the liquid has been added, bring it back up to a simmer and simmer lightly for 5 minutes, or until it is somewhat reduced.
Take the onions off the heat and pour them into a oven-safe dish with a lid. (If you don’t have a Dutch oven or another oven-safe dish with a lid, you can use a baking dish. Just cover it tightly with a double layer of foil.). I prefer to use a shallow dish which gets a better result in the final step when you come to grill the cheese on top of the chicken.
Heat the oven to 160C. While the onions are cooking, brown the chicken. Heat a skillet or fry pan over medium-high heat. Pat the chicken thighs dry and season lightly with salt and black pepper. Add the olive oil to the skillet and when it’s hot, add the thighs and brown for about 3 minutes on each side, 6 minutes total. When they’ve developed a golden-brown crust, remove from the pan and set on top of the caramelized onions in the baking dish.
Add the remaining 1 cup stock to the pan. Stir vigorously, scraping up any browned bits on the bottom of the pan. Whisk in the balsamic vinegar and Dijon mustard. Simmer for about 5 minutes or until reduced by half. Pour this sauce over the chicken and onions, and put the lid on the baking dish. The chicken and onions will look quite saucy; there will be plenty of liquid in the baking dish.
(At this point you can refrigerate the dish for up to 48 hours. Let it sit at room temperature for at least 15 minutes before baking, or else add about 5 minutes to the bake time.)
Bake for 45 minutes. Remove the chicken from the oven and turn on the grill element. Take the lid off the baking dish, and sprinkle the cheese evenly over the top of the chicken. When the griller has heated up, return the dish to the oven and grill for about 5 minutes, or until the cheese is melted and golden on top. Serve hot with plenty of crusty bread on the side.