Ingredients:

  • 1 lb mixed mushrooms (Cremini and Shiitake), sliced
  • 1 cup leeks, white and light green parts only, thinly sliced
  • 3 tbsp unsalted butter
  • 3 cloves garlic, minced
  • 1 tsp fresh thyme leaves
  • 1/2 tsp salt
  • 1/4 tsp black pepper
  • 6 cups sourdough or French bread, cut into 1-inch cubes
  • 1½ cups Gruyère cheese, grated
  • 5 large eggs
  • 2 cups whole milk
  • 1/2 cup heavy cream
  • 1/2 tsp salt
  • 1/4 tsp nutmeg, grated

Instructions:

  1. If using fresh bread, spread the 6 cups of bread cubes on a baking sheet and toast at 300°F (150°C) for 10-15 minutes until dry but not browned.
  2. Melt 3 tbsp unsalted butter in a large pan over medium heat. Add 1 cup sliced leeks and cook for 5–7 minutes until soft and translucent.
  3. Increase heat to medium-high and add 1 lb sliced mixed mushrooms. Cook without stirring for 3 minutes to sear, then sauté for another 5 minutes until liquid has evaporated and mushrooms are golden brown.
  4. Stir in 3 cloves minced garlic and 1 tsp fresh thyme; cook for 1 minute until fragrant. Season with 1/2 tsp salt and 1/4 tsp black pepper.
  5. In a large bowl, whisk together 5 large eggs, 2 cups whole milk, 1/2 cup heavy cream, 1/2 tsp salt, and 1/4 tsp grated nutmeg until the mixture is smooth and pale yellow.
  6. Fold the toasted bread cubes, sautéed mushroom mixture, and 1½ cups grated Gruyère cheese into the custard. Gently stir to ensure all bread is coated.
  7. Let the mixture rest at room temperature for 30 to 45 minutes, stirring once halfway through, until no liquid pools at the bottom of the bowl.
  8. Preheat the oven to 350°F (180°C). Grease a 12-inch cast iron skillet or 3-quart baking dish and transfer the mixture, pressing down slightly to flatten the top.
  9. Bake for 30–35 minutes until the top is a deep golden brown and the center is set (no jiggle) and reaches an internal temperature of 160°F (71°C).
  10. Remove from the oven and let the pudding rest for 10–15 minutes before slicing into 6 squares.