“My Scottish grandmother was renowned for her baking, and one of the highlights whenever we visited my grandparents was her bringing out the baking tin. Her shortbread cookies were my favorite, and now, whenever I make them, I remember her. This is not a thin, crispy dessert shortbread; it’s a deep bar that is best served with a cup of tea.” —Jane Kelly, Wayland, Massachusetts
Preheat oven to 300°. Cream butter and sugar until light and fluffy, 5-7 minutes. Combine flours; gradually beat into creamed mixture. Press dough into an ungreased 13x9-in. baking pan. Prick with a fork.
Bake until light brown, 45-50 minutes. Cut into 48 bars or triangles while warm. Cool completely on a wire rack.