1 1/4 cups all purpose flour
1/2 teaspoon salt
1/2 cup (1 stick) chilled unsalted butter, cut into pieces
2 tablespoons (about) ice water
1 cup water
1 ounce dried porcini mushrooms
1/4 cup (1/2 stick) unsalted butter
10 ounces crimini or button mushrooms, sliced
1/4 cup minced shallots
2 tablespoons Cognac or brandy
2 tablespoons chopped fresh herbs
2/3 cup grated Gruyère cheese
3/4 cup whipping cream
2 large egg yolks
1 large egg
Blend flour and salt in processor. Cut in butter using on/off turns until mixture resembles coarse meal. Add enough water to blend dough. Gather dough into ball; flatten into disk. Wrap in plastic, chill 45 minutes.
Roll out dough on floured surface to 12-inch round. Transfer to 9-inch-diameter tart pan with removable bottom. Trim edges, leaving 1/2-inch overhang. Fold overhang in to form double-thick sides. Press tart edges to raise dough 1/8 inch above pan. Chill 30 minutes.
Bring 1 cup water to boil in saucepan. Add porcini; remove from heat and let stand 30 minutes. Spoon porcini from liquid; reserve liquid. Coarsely chop porcini.
Melt butter in heavy large skillet over high heat. Add porcini and crimini mushrooms. Season with salt; sauté until deep golden, about 10 minutes. Add shallots; sauté 2 minutes. Add Cognac and reserved porcini liquid, leaving any sand behind in saucepan. Boil until almost all liquid is absorbed, about 3 minutes. Mix in 1 tablespoon herbs. Cool.
Preheat oven to 375°F. Line crust with foil. Fill with dried beans; bake until golden, about 15 minutes. Maintain oven temperature.
Sprinkle 1/3 cup cheese in crust. Cover with mushrooms. Whisk cream, yolks, egg and 1 tablespoon herbs in bowl. Pour custard over mushrooms. Top with remaining cheese. Bake until filling is set and top is golden, about 30 minutes. Cool on rack 15 minutes.