1. To prepare crust, weigh or lightly spoon potato starch and flour into dry measuring cups; level with a knife. Combine potato starch, flour, granulated sugar, and salt in a medium bowl; stir with a whisk. Cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Add milk; toss with a fork until moist. Gently press mixture into a 4-inch circle on 2 sheets of heavy-duty plastic wrap that overlap; cover with additional overlapping plastic wrap. Chill 1 hour.
2. Preheat oven to 350°.
3. Roll dough, still covered, into a 12-inch circle. Fit dough, plastic wrap side up, into a 9-inch pie plate coated with cooking spray. Remove remaining plastic wrap. Press dough against bottom and sides of pan. Fold edges under or flute decoratively. Chill until ready to fill.
4. To prepare filling, combine maple syrup and next 5 ingredients (through eggs) in a large bowl, stirring with a whisk. Stir in pecans; pour into prepared piecrust. Bake at 350° for 30 minutes. Shield edges of piecrust with foil; bake an additional 25 minutes or until filling is puffed and golden brown. Cool completely on a wire rack.