Peel and mince fresh ginger. Place in a medium bowl, and blend with flour, sugar, allspice and salt. Cut in butter until mixture resembles coarse meal.
Mix egg yolk and 2 tablespoons water in small bowl. Add yolk mixture to flour and butter mixture; blend until mixture forms moist clumps. If dough is too dry, blend in more water by teaspoonfuls. Gather dough into ball; flatten into disk. Wrap in plastic; chill 1 hour.
Please note: Crust can be made 1 day ahead. Keep chilled. Soften dough slightly at room temperature before rolling.
Preheat oven to 350°F. Roll out dough on floured surface to 12-inch-diameter round. Transfer dough to 9-inch-diameter glass pie dish. Trim overhang to 1 inch. Fold edges under crust. Crimp decoratively, forming high-standing rim (about 1/2 inch above rim of dish).
Freeze crust for 15 minutes. Line crust with foil and then fill with pie weights (dried beans work well too). Bake crust 10 minutes. Remove foil and beans and bake until crust is set and pale golden, about 10 minutes. Transfer crust to rack and cool completely.
Whisk all ingredients in large bowl until combined. Pour into pie crust. Bake until skin begins to form on filling and filling begins to set, about 50 minutes. Remove from oven. Let pie stand 10 minutes to set slightly. Maintain oven temperature.
Meanwhile, prepare topping:
Mix first 5 ingredients in medium bowl. Rub in butter with fingertips until mixture begins to form small clumps. Sprinkle topping over pie. Bake until pie is set and streusel is golden brown, about 25 minutes. Transfer to rack and cool completely.
Serve with homemade Organic Valley Whipped Cream or use the Spiced Whipped Cream recipe used for the Cobbler. Enjoy!