Crab Quiche

Blend together flour, butter, shortening, and salt in a bowl with your fingertips or a pastry blender (or pulse in a food processor) just until most of mixture resembles coarse meal with some roughly pea-size butter lumps. Drizzle evenly with 3 tablespoons ice water and gently stir with a fork (or pulse in processor) until incorporated.
Squeeze a small handful: If it doesn't hold together, add more ice water, 1/2 tablespoon at a time, stirring (or pulsing) until just incorporated, then test again. (Do not overwork mixture, or pastry will be tough.)
Turn out mixture onto a work surface and divide into 4 portions. With heel of your hand, smear each portion once or twice in a forward motion to help distribute fat. Gather dough together with scraper and press into a ball, then flatten into a 4-inch disk. Chill dough, wrapped in plastic wrap, until firm, at least 1 hour.
Roll out dough into a 12-inch round on a lightly floured surface with a floured rolling pin and fit into pie plate. Trim excess dough, leaving a 1/2-inch overhang, then fold overhang under pastry and press against rim of pie plate to reinforce edge. Decoratively crimp edge and lightly prick bottom and side of shell with a fork. Chill until firm, about 30 minutes.
Put oven rack in middle position and preheat oven to 375°F.
Line shell with foil and fill with pie weights. Bake until pastry is pale golden along rim and set underneath foil, about 20 minutes. Carefully remove foil and weights and bake shell until bottom and side are pale golden, about 10 minutes more. Cool completely in pie plate on a rack, about 20 minutes.
If using crab leg, hack through shell with a large heavy knife and cut meat into 1/2-inch pieces. Discard shell.
Whisk together eggs, cream, herbs, seafood seasoning, salt, pepper, and nutmeg, then stir in cheeses and crabmeat.
Pour into prebaked crust and bake until filling puffs and is no longer wobbly in center when quiche is gently shaken, 40 to 50 minutes. Cool in pie plate on rack 15 minutes.