How to Make It
Preheat oven to 425°.
To prepare crust, lightly spoon 1 cup flour into a dry measuring cup; level with a knife. Combine 1 cup flour, 2 tablespoons sugar, and salt in a bowl; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal. Sprinkle surface with ice water, 1 tablespoon at a time; toss with a fork until moist and crumbly (do not form a ball).
Press mixture gently into a 4-inch circle on heavy-duty plastic wrap; cover with additional plastic wrap. Roll dough, still covered, to a 12-inch circle. Freeze 10 minutes or until plastic wrap can be easily removed.
Remove 1 sheet of plastic wrap; fit dough into a 9-inch pie plate coated with cooking spray. Remove top sheet of plastic wrap. Fold edges under; flute. Line dough with a piece of foil; arrange pie weights (or dried beans) on foil. Bake at 425° for 10 minutes or until edge is lightly browned. Remove pie weights and foil; reduce oven temperature to 350°. Bake crust an additional 5 minutes; cool on a wire rack.
To prepare filling, combine 1 cup sugar and next 6 ingredients (1 cup sugar through egg whites) in a bowl; stir with a whisk until well-blended. Gradually stir in buttermilk. Pour into prepared crust. Bake at 350° for 40 minutes or until set, shielding crust with foil after 30 minutes, if necessary. Cool on a wire rack.