Ingredients:

  • 3 tbsp (42g) unsalted butter
  • 2 cups (150g) leeks, white and light green parts only, thinly sliced
  • 2 cloves garlic, minced
  • 1 tsp (2g) kosher salt
  • 1/2 tsp (1g) black pepper
  • 8 large eggs
  • 2 cups (480ml) heavy cream
  • 1 tbsp (15ml) Dijon mustard
  • 1 tsp (2g) fresh thyme leaves
  • 1 lb (450g) sourdough bread, cut into 1-inch cubes
  • 2 cups (225g) Gruyère cheese, grated
  • 1/2 cup (40g) Parmesan cheese, freshly grated

Instructions:

  1. Melt the butter in a skillet over medium heat. Add the sliced leeks and cook until translucent and soft (about 5 to 7 minutes). Stir in the minced garlic, salt, and pepper, cooking for another 60 seconds until fragrant. Remove from heat and let cool slightly.
  2. Grease a 9x13 inch ceramic baking dish. Scatter half of the sourdough cubes across the bottom. Layer the sautéed leeks and half of the Gruyère cheese over the bread. Top with the remaining bread cubes and the rest of the Gruyère.
  3. Whisk the eggs, heavy cream, Dijon mustard, and thyme together until completely smooth. Pour the mixture evenly over the bread, pressing down with a spatula to ensure every cube is submerged.
  4. Cover the dish with foil and refrigerate overnight (at least 8 hours).
  5. Preheat the oven to 350°F (175°C). Bake the strata uncovered for 40-45 minutes until the top is puffed, set, and mahogany-colored.