1Heat oven to 350°F. Line 13x9-inch pan with foil, allowing edges to hang over pan; spray foil with cooking spray.
2In large bowl, stir together flour blend, oats, sugar, xanthan gum and salt. Cut in cold butter, using pastry blender (or pulling 2 table knives through mixture in opposite directions) until mixture looks crumbly. Stir in cold water just until moistened (mixture will remain crumbly). Pat mixture in bottom of pan.
3Bake 15 minutes. Spread sweetened condensed milk over hot crust. Sprinkle chips, cranberries and pistachio nuts evenly over milk. Press toppings down with fork.
4Bake 25 to 30 minutes longer or until light brown. Cool on cooling rack. Lift out of pan by foil hanging over edges. Cut into 8 rows by 5 rows.