Combine the dates and walnuts; put through a food grinder.
Sift the flour with the sugar, baking powder, and salt.
Add the ground dates and nuts; mix well to coat.
Beat the eggs until light.
Stir in the margarine.
Add the date mixture and mix thoroughly.
Turn the mixture into a well-greased and floured 9 x 9 x 2-inch baking pan.
Bake in a 350° oven for about 40 minutes.
The top should be a medium-brown color.
Cool in the pan set on a rack, then cut into 1 1/2-inch squares and roll in confectioners' sugar.