Add the flour sugar and salt to the nuts and pulse until just mixed. Add the egg, butter, and maple syrup and mix. Line a sheet pan with parchment and press the dough into a 12 1/2 x 9 1/2 inch rectangle 1/4 inch thick. Cut into 40 squares 6x8. Place in the freezer for 10 minutes. Line another sheet pan with parchment. Remove the cookies from the freezer and place them on a sheet pan 1 inch apart. Bake for 12 minutes. Remove from oven, cool, and fill with date caramel.