Beat together the butter, sugar, and egg until very light and fluffy.
Put one cup dates in a two cup measure, pressing lightly to measure. Pour in applesauce to fill to the two cup line, stirring and adding applesauce as the gaps between the dates are filled in.
Pour the date and applesauce mixture into the beaten butter mix and stir until well combined.
Sift or stir together the flour, baking powder, baking soda, and spices. Add to the date/applesauce/butter mixture and stir just until completely combined. Don't overly beat. If using walnuts, stir them in just before putting batter in pan.
Spray or oil a 7 X 11 or 9 x 9 inch pan and pour the batter into it. The batter will be thick so carefully smooth it so it is as even as possible.
Bake in a preheated 350 degree oven for 22 to 25 minutes.
When well cooled, sprinkle with powdered sugar OR spread a thin layer of powdered sugar glaze over the top.