To prepare pastry, lightly spoon 1 1/4 cups flour into dry measuring cups; level with a knife. Place 1 1/4 cups flour, granulated sugar, and 1/2 teaspoon salt in a food processor. Process 10 seconds. Add butter; pulse 4 times or until mixture resembles coarse meal. Place flour mixture in a bowl. Sprinkle surface with ice water, 1 tablespoon at a time; toss with a fork until moist. Place pastry on a lightly floured surface; knead lightly 3 or 4 times. Gently press mixture into a 4-inch circle on plastic wrap; cover. Chill for 30 minutes.
Slightly overlap 2 sheets of plastic wrap on a slightly damp surface. Unwrap and place chilled dough on plastic wrap. Cover with 2 additional sheets of overlapping plastic wrap. Roll dough, still covered, into an 11-inch circle. Place dough in freezer 5 minutes or until plastic wrap can be easily removed.
Preheat oven to 350°.
Remove top sheets of plastic wrap; fit dough, plastic wrap side up, into a 9-inch pie plate. Remove remaining plastic wrap. Fold edges under; flute. Line bottom of dough with a piece of foil coated with cooking spray; arrange pie weights or dried beans on foil. Bake at 350° for 15 minutes. Remove pie weights and foil; cool pastry on a wire rack.
To prepare filling, combine sweet potatoes and next 4 ingredients (through egg white) in a food processor; process until blended. Spoon into a large bowl. Add 1% milk and remaining ingredients; stir well. Pour filling into pastry. Bake at 350° for 50 minutes or until a knife inserted in center comes out clean. Cool completely on a wire rack.