inspired by Noble Pig
Serves 8-10
8 cups bread cubes from a rustic country loaf, 1/2" dice (I used a rosemary garlic bread)
2 Tablespoons olive oil
1 Tablespoon butter
2 ounces thick-cut bacon, diced (I used four thick slices, about 5 ounces)
4 cups sliced leeks white and green parts (about 4-6 leeks)
1-1/2 pounds cremini mushrooms, sliced (I used 1 pound)
1 Tablespoon chopped fresh sage
1/4 cup dry white wine
Kosher salt and freshly ground pepper
1/3 cup minced fresh-flat leaf parsley
6 large eggs
1-1/2 cups heavy cream
1 cup chicken stock
8 ounces grated Gruyere cheese, divided
Preheat oven to 350 degrees F. Spread the bread cubes on a sheet pan and bake for 20 minutes until dried out and lightly browned. Set aside.
Meanwhile, heat the oil and butter in a large 12" skillet saute pan over medium heat. Add bacon and cook for 5 minutes, until starting to brown. Stir in leeks and cook over medium for 10 minutes, until they are tender. Stir in mushrooms, sage, white wine, 1 Tablespoon Kosher salt and 1-1/2 teaspoons pepper and cook for 12 minutes, until most of the liquid evaporates, stirring occasionally. Off the heat, stir in the parsley. Pour mixture over bread crumbs on baking tray to cool down slightly.
In a large mixing bowl, whisk together eggs, cream, chicken stock, and half of the Gruyere cheese. Add the bread cubes and mushroom mixture, stirring well to combine. Set aside at room temperature for 30 minutes to allow the bread to absorb the liquid . Stir well and pour into a 3 quart gratin dish (13 x 9). Sprinkle with remaining cheese and bake for 45 to 50 minutes until the top is browned and the custard is set. Serve hot.