Preheat oven to 375 degrees F (190 degrees C).
Mix together the flour, hazelnuts, baking powder, spices and salt. In a large bowl, cream the shortening and powered sugar. Beat in the lemon zest. Gradually stir in the dry ingredients. Press the dough into an ungreased 9-inch square baking pan.
Bake for 18 to 20 minutes, until the top is golden. Let cool in the pan or on a wire rack.