Ingredients:

  • 1 large yellow onion, thinly sliced (150g)
  • 2 tbsp unsalted butter (28g)
  • 1 tsp olive oil (5g)
  • 1/4 tsp kosher salt (1.5g)
  • 1 sprig fresh thyme, leaves removed (1g)
  • 4 slices sourdough bread (approx. 1 inch thick)
  • 4 oz sharp cheddar or Gruyère, shredded (113g)
  • 1/2 medium pear, thinly sliced (60g)
  • 1/2 medium Granny Smith apple, thinly sliced (60g)
  • 3 tbsp salted butter, softened for grilling (42g)

Instructions:

  1. Melt 2 tbsp butter and olive oil in a saucepan over medium-low heat. Add sliced onions and salt.
  2. Cook onions, stirring occasionally, for 15–20 minutes until they reach a deep mahogany color and jam-like consistency.
  3. Stir in thyme leaves during the last 2 minutes of cooking, then remove from heat.
  4. Spread softened butter evenly on one side of each sourdough slice.
  5. Flip the slices over and sprinkle a generous layer of shredded cheese on the unbuttered side.
  6. Layer thin slices of pear and apple over the cheese, followed by a heap of caramelized onions, and top with another layer of cheese.
  7. Close the sandwiches and place them in a cold cast iron skillet.
  8. Turn the heat to medium-low and grill for 3–5 minutes per side, pressing down gently with a spatula.
  9. Flip once the bread is mahogany-brown and cheese has begun to ooze, removing when the crust sounds hollow when tapped.