Preheat the oven to 350 degrees. Grease a 10-by-15-inch jelly roll pan. In a large bowl, beat the egg. Stir in the sugar, oil and dates. In a medium bowl, stir together the flour, baking soda, salt and spices. Add the egg mixture and the pumpkin puree alternately to the flour mixture in thirds, stirring to blend well each time. Stir in the nuts. Pour the batter into the prepared pan and spread it evenly with a spatula. Bake until well browned and a toothpick inserted in the center comes out clean, about 25 minutes. Transfer the pan to a rack to cool for about 5 minutes. To make the glaze: in a small bowl, mix the confectioners' sugar and lemon juice. If the glaze seems too thick, add a little more sugar. Spread the glaze over the baked layer. Let stand for 5 minutes, then cut into bars about 3 inches by 1 1/2 inches. Makes about 30 bars.
Source: "Holiday Pumpkins" by Georgeanne Brennan & Jennifer Barry