Season 6 trout to taste with salt and freshly ground black pepper. Line a well-buttered baking dish with a mixture of 1 teaspoon each finely chopped parsley, onion, chives, and chevril, 3 generous tablespoons raw mushrooms, finely chopped, and a few leaves of tarragon. Place the fish on top of the vegetables and pour over them 2 tablespoons softened butter. Cover the dish with a buttered paper and set in a hot oven for 10 minutes.
Beat well 4 egg yolks and add 3 tablespoons of brandy. Remove paper and pour the egg and brandy over the fish. Sprinkle with 5 tablespoons soft bread crumbs mixed with 5 tablespoons grated Swiss cheese and a little paprika. Return the dish to the oven to brown the crumbs. Serve the trout in the baking dish, with a side dish of grilled tomato slices and grilled tomato slices and grilled large onions, each topped with a grilled mushroom.