½ oz package dried porcini mushrooms
1 cup water
2 Tbsp DLM Extra-Virgin Olive Oil
4 Tbsp butter , plus more for buttering pan
8 oz mushrooms, sliced
2 shallots, thinly sliced
8 fresh sage leaves
Salt and pepper, to taste
3 leeks (white and pale green parts only), washed and thinly sliced
6 eggs
1½ cups cream
1½ cups milk
¼ tsp Cayenne pepper
2 oz Gruyère or Emmental cheese, shredded
1½ loaves DLM Brioche, sliced and crust removed
½ cup Parmigiano-Reggiano , grated

In a pot, bring one cup water to a boil. Add the dried porcini mushrooms and let soak for 10 minutes. Remove mushrooms, chop, and set aside. Reserve mushroom water and set aside as well.
In a large sauté pan, heat the 2 tablespoons olive oil and 2 tablespoons of butter. Add the mushrooms and cook until golden brown. Add the shallots and continue to cook for 3-4 minutes until softened. Stir in the sage and chopped porcinis. Season generously with salt and pepper to taste. Remove from heat and transfer to a bowl. Place the same sauté pan back on heat and add to it another 1-2 tablespoons of butter. Add the leeks, seasoning with salt until wilted, about 5 minutes. Add to the mushroom mixture.
In a separate large bowl, crack the eggs and whisk with the reserved mushroom water. Add the cream, milk, and Cayenne pepper. Season again to taste with additional salt and pepper. Stir in the Gruyère.
Grease the bottom and sides of a 9x13-inch baking dish with butter, then add about 1/4 of the fresh mushroom mixture and arrange in an even layer. Layer the bread slices on mixture in an overlapping pattern. Sprinkle the remaining mushroom mixture over top, tucking it in between the bread slices. Ladle the custard mixture over top, evenly distributing the cheese.
Give the casserole at least 30 minutes at room temperature before baking. Brioche will quickly absorb the egg custard, but for a more tender overall casserole refrigerate overnight.
When ready to cook, preheat the oven to 350°F and remove the dish from the refrigerator about 30 minutes before baking. Top the strata with the Parmigiano-Reggiano and bake for 45-50 minutes. Let sit at least 5 minutes before cutting to help set up.