Combine dates, water, and maple syrup in a heavy saucepan over medium heat. Bring to a boil; cook 12 minutes or until most liquid is absorbed, stirring frequently (will resemble jam). Stir in zest. Let cool completely.
Beat sugar and butter at medium mixer speed until smooth.
Place flour, oats, baking soda, and salt in a medium bowl and whisk to blend. Add the flour mixture to the butter mixture. Mix slowly until crumbly.
Press 2 cups of the flour mixture into the bottom of a 13 x 9” glass or ceramic baking dish that’s been lightly buttered. Spread date mixture over flour mixture. Sprinkle with the remaining flour mixture.
Bake for 20 minutes or until golden brown. Cool completely in pan on a wire rack. Cut into squares and store in a cookie tin between layers of wax paper.