Ingredients:

  • large yellow onions (about 3 lbs total), thinly sliced pole-to-pole
  • tablespoons unsalted butter
  • tablespoons olive oil
  • /2 cup dry sherry or dry white wine (optional)
  • cups high-quality beef broth/stock
  • teaspoon dried thyme
  • large bay leaves
  • teaspoon Worcestershire sauce
  • Salt and freshly ground black pepper to taste
  • loaf baguette or crusty French bread, sliced into 1-inch thick rounds
  • cups freshly shredded Gruyère cheese
  • tablespoon fresh parsley, chopped, for garnish

Instructions:

  1. In a large skillet over medium heat, melt the butter with the olive oil. Add the sliced onions and a pinch of salt. Sauté for 10 minutes until softened and lightly golden.
  2. Pour in the sherry/wine (if using). Scrape up any browned bits from the bottom of the skillet. Cook until the liquid has nearly evaporated (about 2 minutes).
  3. Transfer the softened onions into the slow cooker insert. Add the beef broth, dried thyme, bay leaves, and Worcestershire sauce. Stir gently to combine.
  4. Cover and cook on Low for 8–10 hours or High for 4–5 hours. The onions should be deeply brown, sweet, and very tender.
  5. Remove and discard the bay leaves. Taste the broth and adjust seasoning with salt and pepper as needed. Keep the soup warm on the 'Keep Warm' setting.
  6. Preheat your oven broiler. Arrange bread slices on a baking sheet. Broil for 1–2 minutes per side until lightly toasted and crisp.
  7. Ladle the hot soup into oven-safe crocks. Float one or two toasted bread slices on top of the broth.
  8. Generously top the bread with shredded Gruyère cheese, ensuring the cheese touches the edges of the bowl.
  9. Place the crocks carefully under the preheated broiler for 2–4 minutes, watching constantly, until the cheese is melted, bubbling, and deeply golden brown. Garnish immediately with fresh parsley and serve carefully as it will be piping hot.