Position rack in the center of the oven. Preheat oven to 375 degrees. Grease a large cookie sheet.
Whisk together thoroughly flour, baking powder, and salt.
Beat on medium speed until well blended: butter or oil, sugar, eggs, egg whites, lemon and orange zest, almond extract and vanilla.
Gradually stir the flour mixture into the egg mixture adding nuts and chocolate until well blended. Shape the dough into three smooth, evenly shaped logs with lightly floured hands. Arrange the logs as far apart as possible on the sheet and press to flatten slightly.
Bake 25 minutes. Remove the sheet to a rack. When cool enough to handle, carefully transfer to a cutting board and cut crosswise on a slight diagonal, into 3/8 inch thick slices. Lay slices flat on the sheet. Return to the oven and bake 10 minutes more. Turn the slices over and bak until lightly brown - 5 to 10 minutes. Turn off oven
open door and leave cookies in oven until cool. This makes a dry, crisp cookie that can be stored in the refrigerator up to 30 days.