In a small bowl combine boiling water and dates. Cover and let stand for 10 minutes. Drain.
Coat an 8x8x2-inch baking pan with cooking spray; set aside. Combine flour, baking powder, cinnamon, and baking soda; set aside.
In a medium mixing bowl beat egg with an electric mixer on high speed until frothy. Add brown sugar; beat until combined. Stir in evaporated milk and drained dates.
Add flour mixture to egg mixture, stirring with a wooden spoon until combined. Stir in nuts. Pour batter into the prepared baking pan.
Bake in a 350 degree F oven about 15 minutes or until a wooden toothpick inserted near the center comes out clean. Cool in pan on a wire rack. Sprinkle with powdered sugar. Cut into bars. Makes about 24 bars.