Beat butter at medium speed with an electric mixer until creamy; gradually add sugar, beating well. Add egg yolks, beating just until blended.
Combine baking soda and milk, stirring until soda dissolves; add orange juice.
Combine flour and next 4 ingredients. Combine 1/2 cup flour mixture, dates, and next 4 ingredients, tossing gently to coat.
Add remaining flour mixture to butter mixture, alternately with milk mixture, beginning and ending with flour mixture. Gradually stir fruit mixture into batter.
Beat egg whites at high speed with an electric mixer until stiff peaks form; fold into batter.
Drop dough by level tablespoonfuls onto lightly greased baking sheets.
Bake at 300° for 15 to 18 minutes or until lightly browned.
Note: Cookies may be stored in an airtight container up to 1 week or frozen up to 3 months.