Grease 15cm by 25cm load pan, line base with greaseproof paper. Beat oil, sugar & eggs in small bowl with electric mixer until thick & creamy. Transfer mixture to large bowl, stir in carrot, nuts & raisins, then sifted dry ingredients. Pour mixture into prepared pans, bake in moderate oven 45 minutes. Cover loosely with foil, bake about 45 minutes. Stand a few minutes before turning onto wire rack to cool. Top cold cake with cream cheese frosting.
Beat butter, cheese, rind & juice in small bowl with electric mixer, beat until light & fluffy; gradually beat in sifted icing sugar.