This sinfully rich and buttery shortbread from an Irish cook. It’s rather thicker than some but still beautifully baked through. If you should have trouble finding the rice flour, try a Chinese grocery or specialty shop – it is labeled “glutinous rice powder” and is called “sweet.” Many shortbreads are made with sweet butter but this one is not.
Beat butter and sugar until very light and creamy. Add sifted flours and mix gently but thoroughly by hand. Pack into an ungreased 8- or 9-inch square tin. When the dough is smoothly packed, go around the sides with a thin-bladed spatula, running it between the dough and the walls of the pan. Cut dough all the way through into small rectangles, then prick each rectangle with the tines of a fork. Bake in a 325 degrees F oven for 50 or 55 minutes, until the shortbread is golden. Cut through again at the original markings while the cookies are still hot, but don’t try to remove them from the pan until they cool.