¾ cup dried sliced porcini (a generous handful), (optional)
1½ cups chicken bone broth or vegetable stock, (if not using dried mushrooms, you only need about ¾ cup)
1 loaf stale bread, peasant-style or baguette (¾ to 1 pound)
3 cloves garlic, 1 halved, 2 chopped
1½ cups whole milk
2 tablespoons extra-virgin olive oil (EVOO)
¼ pound meaty pancetta, chopped (optional)
1 to 1½ pounds Swiss chard, stemmed, stems chopped and leaves coarsely shredded
1 small onion or large shallot, chopped
2 teaspoons lemon zest
Freshly grated nutmeg
1 teaspoon red pepper flakes
Juice of ½ lemon
6 large eggs
White pepper or fine black
4 tablespoons softened butter, for casserole dish
1½ cups grated Gruyere cheese (about 6 ounces)
1 cup grated Parmigiano-Reggiano cheese
Preheat oven to broil.
Place mushrooms and stock in small pot, bring to low boil and reconstitute. Reduce to 1 cup, then remove mushrooms to cool and finely chop them. Reserve broth.
Thick slice bread into 1-inch pieces and arrange on baking sheet and char it to quickly toast. Rub with the large clove of halved garlic, dice into pieces, and add to a bowl. Turn off broiler. Moisten the bread with ¾ cup milk, about ½ of the total amount.
Heat a large skillet with EVOO, 2 turns of the pan, add pancetta (optional), render 2 minutes then add chard stems, shallots or onion, lemon zest, and salt. Soften 5 minutes, wilt in the chard greens, then add a little freshly grated nutmeg, the chopped garlic, the chopped mushrooms, red pepper flakes, and juice of ½ lemon. Remove from heat.
Whisk up eggs, the remaining ¾ cup milk, ¾ cup of the stock (discard the last ¼ cup of the stock as grit may settle here if you used mushrooms), and season with salt and white pepper or fine black pepper.
Butter a casserole dish and fill with half the bread, half the greens, pour over half the egg mixture, then sprinkle with half of each of the cheeses and repeat. Cover with parchment and foil or plastic and refrigerate 1 hour to overnight.
Preheat oven to 350˚F and bake 50 to 60 minutes uncovered until firm and brown and evenly cooked through.