Heat oven to 350°F (325°F for dark pan). In ungreased 13x9-inch pan, break up cookie dough. With floured fingers, press dough evenly in bottom of pan. Bake 13 to 15 minutes or until edges are golden brown.
Meanwhile, in large bowl, beat eggs with wire whisk. Stir in brown sugar, flour and syrup until well blended. Stir in walnuts.
Pour egg mixture evenly over partially baked crust; bake 30 to 35 minutes longer or until filling is set. Cool completely on wire rack, about 1 hour 30 minutes. If desired, sprinkle with powdered sugar. Cut into 6 rows by 6 rows.