Mix dry ingredients with the butter or margarine, (like pie dough) and add the beaten egg yolks, sour cream and vanilla. Work dough well. Press dough into bottom of large cookie sheet, using more than half of dough for bottom. Cover with favorite jelly or jam. Make criss-cross design by rolling pencil thickens or less by hands on board. Bake at 350ºF. for 30 minutes until lightly browned on top. When cooled, cut into squares and sprinkle with sifted powdered sugar.