Line bottom and sides of a 13 x 9inch baking pan with foil; coat foil with cooking spray, and set aside.
Weigh or lightly spoon flour into dry measuring cups; level with a knife.
Combine flour, cornstarch, and salt in a large bowl; stir with a whisk.
Place butter in a medium bowl; beat with a mixer at medium speed 2 minutes or until light and fluffy.
Add oil; beat with a mixer at medium speed 3 minutes or until well blended. Gradually add sugar, beating well. Scrape seeds from vanilla bean, and add seeds to butter mixture; discard bean.
Add flour mixture, beating at low speed just until blended. Spoon dough into prepared pan.
Place a sheet of heavy-duty plastic wrap over dough; press to an even thickness. Discard plastic wrap.
Bake at 350 for 30 minutes or until edges are lightly browned. Cool in pan 5 minutes on a wire rack; cut into 32 pieces. Carefully lift foil from pan; cool squares completely on a wire rack.
