Ingredients:

  • 2 lbs (900g) yellow onions, thinly sliced
  • 4 tbsp (56g) unsalted butter
  • 2 tbsp (30ml) olive oil
  • 1 tsp granulated sugar
  • 1/2 tsp kosher salt (plus more to taste)
  • 1/4 tsp black pepper (plus more to taste)
  • 1/4 cup (60ml) dry Sherry or dry white wine (optional)
  • 8 cups (2 liters) beef broth, low sodium
  • 2 sprigs fresh thyme
  • 1 bay leaf
  • 6-8 slices baguette, cut into 1-inch thick rounds
  • 2 tbsp olive oil
  • 4 ounces (115g) Gruyère cheese, grated

Instructions:

  1. Melt butter and olive oil in a large pot. Add onions, sugar, salt, and pepper. Cook over medium-low heat, stirring occasionally, until deeply caramelized, about 45-60 minutes.
  2. If using Sherry or wine, pour it into the pot and scrape up any browned bits from the bottom. Cook until the liquid is almost evaporated.
  3. Pour in beef broth. Add thyme and bay leaf. Bring to a simmer, then reduce heat and simmer for at least 30 minutes, or up to an hour.
  4. Preheat oven to 375°F (190°C). Toss baguette slices with olive oil. Bake on a baking sheet until lightly toasted, about 8-10 minutes.
  5. Remove thyme sprigs and bay leaf from the soup. Ladle soup into oven-safe bowls or ramekins. Top each bowl with toasted baguette slices and generous amounts of Gruyère cheese.
  6. Broil in the oven until the cheese is melted, bubbly, and lightly browned, about 2-3 minutes. Watch carefully to prevent burning!
  7. Allow to cool for a minute or two before serving this delicious onion soup recipe.