A comforting and flavorful twist on classic French onion soup, this French Onion Chicken Soup is a hearty and cheesy soup that will warm you up on chilly days.
Caramelize Onions: In a large pot, melt the butter with the olive oil over medium heat. Add the sliced onions, sugar, and salt. Cook, stirring occasionally, for 25–30 minutes until deeply caramelized.
Add Flavors: Stir in the garlic and thyme, cook for 1 more minute. Pour in the chicken broth and bring to a simmer.
Finish Soup: Add the shredded chicken, balsamic vinegar, and black pepper. Simmer for 10–15 minutes to meld flavors.
Prepare Bread and Cheese: Meanwhile, toast the bread slices until golden. Ladle the soup into oven-safe bowls, place a toast slice on top of each, and sprinkle generously with Gruyère cheese.
Broil: Broil for 2–3 minutes until the cheese is melted and bubbly. Serve hot.
Notes
For extra richness, add a splash of white wine after caramelizing the onions.