1. Preheat oven 150c.
2. Beat butter in a bowl with a wooden spoon to soften, then add sugar, flour, oats and semolina, then mix well.
3. Divide the mixture into two round 20cm diameter oven dishes. Lightly press the mixture evenly, your finger tips first, then use back of spoon. make sure the mixture flat and firm. Finally, prick the shortbread all over with fork.
4. Bake the shortbread about 15mins or until it turns pale gold, feel firm in the centre. Then remove from the oven and using knife make out the surface into 12 wedges. Leave it to cool in the dishes, then dredges with the golden caster sugar.