Preheat oven to 375°F. Mix cornstarch, sorghum flour, tapioca flour, xanthan gum, baking soda and salt in medium bowl. Set aside. Beat butter and sugars in large bowl with electric mixer on medium speed until light and fluffy. Add eggs and vanilla; mix well. Gradually beat in flour mixture on low speed until well mixed. Stir in chocolate chips.
Drop by rounded tablespoons about 2 inches apart onto ungreased baking sheets.
Bake 8 to 10 minutes or until lightly browned. Cool on baking sheets 1 minute. Remove to wire racks; cool completely.