Beat butter, essence and sugar in small bowl with electric mixer until light and fluffy. Transfer into large bowl. Stir in sifted flours into batches. Press mixture together firmly. Turn dough onto lightly floured surface, knead for three minutes. Divide mixture in half, roll each half on greased oven tray until 18 centimeters round, push into shape, pinch edges. Mark eight wedges on surface of each round, prick with fork. Bake in moderately slow oven for about 1 1/4 hours or until lightly brown. Cool before breaking into wedges.