1. Preheat oven to 375°F.
2. Cream together butter and sugar until light and fluffy.
3. Beat in eggs one at a time.
4. Stir in vanilla.
5. Mix together flour, baking powder, and baking soda; and gradually add to the creamed mixture.
6. Fold in the dates and nuts.
7. Spread the batter evenly in a greased 13x9 baking pan and bake at 375°F for 25 minutes or until golden.
8. Cool in pan.
9. Cut into approximately 24 bars.