1. Prepare Crust: Whisk together first 5 ingredients in a medium bowl until well blended. Cut butter into flour mixture with a pastry blender or fork until mixture resembles small peas and is crumbly.
2. Sprinkle cold water, 1 Tbsp. at a time, over surface of mixture in bowl; stir with a fork until dry ingredients are moistened. Place dough on a plastic wrap-lined flat surface, and shape into a disc. Wrap in plastic wrap, and chill 30 minutes.
3. Unwrap dough, and roll between 2 new sheets of lightly floured plastic wrap into a 12-inch circle. Fit into a 9-inch pie plate. Fold edges under, and crimp. Chill 30 minutes.
4. Preheat oven to 400°. Bake crust 20 minutes, shielding edges with aluminum foil to prevent excessive browning. Cool completely on a wire rack (about 1 hour).
5. Meanwhile, prepare Filling: Bake sweet potatoes at 400° on a baking sheet 50 to 55 minutes or until tender. Let stand 5 minutes. Cut potatoes in half lengthwise; scoop out pulp into a bowl. Mash pulp. Discard skins.
6. Whisk together eggs and granulated sugar until well blended. Add milk, next 6 ingredients, and sweet potato pulp, stirring until blended. Pour mixture into Rosemary-Cornmeal Crust.
7. Bake at 400° for 20 minutes. Reduce heat to 325°, and bake 20 to 25 minutes or until center is set. Let cool completely on a wire rack (about 1 hour).
Kitchen Express: Substitute 1/2 (15-oz.) package refrigerated piecrusts for cornmeal crust ingredients. Unroll on a lightly floured surface. Sprinkle with 1 Tbsp. plain white cornmeal and 2 tsp. chopped fresh rosemary. Lightly roll cornmeal and rosemary into crust. Fit into a 9-inch pie plate according to package directions. Fold edges under; crimp. Proceed as directed, beginning with Step 5.