1In food processor, place flour blend, xanthan gum and salt. Cover; process until combined. Add butter; pulse 3 to 5 times or until mixture looks like coarse crumbs.
2In 1-cup measuring cup, beat 1 egg yolk, cider vinegar and 3 tablespoons cold water with fork. With food processor running, quickly pour egg mixture through feed tube, and process a few seconds until dough begins to come together. (Add additional water if necessary.) Remove dough; shape into flattened disk.
3Heat oven to 450°F. On 12-inch square of cooking parchment paper lightly sprinkled with flour blend, roll dough into 11-inch circle. Carefully center ungreased 9-inch pie plate over circle. Turn crust and pie plate over to place crust into pie plate. Remove paper. Ease crust into pan, repairing any tears with wet fingers. Trim overhanging edge of pastry 1 inch from rim of pie plate. Fold and roll pastry under, even with plate; flute as desired. Do not prick. Line crust with double thickness of foil. Bake 8 minutes; remove foil. Bake 4 to 5 minutes longer or until pastry is set and dry. Reduce oven temperature to 325°F.
4For Filling, in medium bowl, beat eggs lightly with whisk or hand beater. Beat in half-and-half, salt and red pepper. Sprinkle broccoli, cheese, ham and onion in partially-baked crust. Pour egg mixture evenly over broccoli mixture. Bake 45 to 50 minutes or until knife inserted near center comes out clean. If necessary, cover edge of crust with foil to prevent overbrowning. Let stand 10 minutes before serving.