To prepare the cream, pour milk into a pan, add semolina and leave for 10 minutes. Stir, put on hob and bring to the boil, add sugar and then cook for 3 min stirring constantly. Leave to cool down. Whisk butter, then whisk in the cool semolina mixture, vanilla extract and whisky. Stick all the cake layers together with the cream putting walnuts on top of each layer of cream. Do not put any cream on top. Each layer of cream will be about 1 cm thick.