Heat oven to 350° F.
Line 9-by-13-inch baking pan with foil; allow overhang. Grease foil with nonstick cooking spray; set aside.
In large bowl, whisk 2 cups flour, 1/2 cup powdered sugar, cornstarch and salt.
Using pastry blender, cut in butter until mixture resembles crumbs. Press mixture into bottom of baking pan. Bake 18-20 minutes.
To make filling: In medium bowl, whisk eggs, sugar, remaining flour, lemon zest, lemon juice and light cream.
Pour filling over hot crust. Bake 15-20 minutes.
Cool completely on wire rack.
Grasp foil overhang and lift from pan. Cut into bars. Sprinkle powdered sugar over bars before serving.