For Crust, in medium bowl, stir together 1 1/2 cups flour blend, 1/2 cup granulated sugar and the xanthan gum. Cut in butter, using pastry blender (or pulling 2 table knives through mixture in opposite directions), until mixture looks like coarse crumbs. Add water, 1 teaspoon at a time, tossing with fork, until crumbly. Press dough in bottom of pan. Bake 20 to 25 minutes or just until set.