Pulse first 3 ingredients in a food processor 3 or 4 times or until combined. Add butter and shortening, and pulse 5 or 6 times or until crumbly. With processor running, gradually add 5 tablespoons water, and process until dough forms a ball and separates from sides of bowl, adding more water if necessary. Cover and chill.
Melt 2 tablespoons butter in a large skillet over medium-high heat. Add mushrooms and shallot; sauté 5 minutes or until mushrooms are tender. Remove mushroom mixture from skillet; set aside. Add scallops to skillet; sauté 3 minutes. Remove with a slotted spoon; set aside.
Whisk together cornstarch and wine in a bowl. Combine cornstarch mixture, cream, and cheese in a large skillet over medium heat; cook 3 minutes or until mixture is thickened. Remove from heat, and stir in mushroom mixture, scallops, rice, and remaining ingredients. Set aside and keep warm.
Divide dough in half. On a lightly floured surface, roll each half to 1/8-inch thickness. Place one half of dough in bottom of a lightly greased 2-quart casserole dish. Spoon scallop mixture over crust. Place other half of dough over filling, pinching to seal edges. Cut slits in top of crust with a knife.
Bake at 350° for 1 hour or until crust is lightly browned. Let stand 10 minutes before serving.
Wine note: Can I pair anything but Riesling? With the sweetness of the hazelnuts, the scallops, and the sauce, i would head straight for a bottle from Germany in the Mosel region. Something like Fritz Haag Brauneberger Juffer-Sonnenuhr Riesling Kabinett 2001 ($27). --Steven Geddes