1.Preheat oven to 180ºC (160ºC fan-forced). Grease shallow 22cm-square cake pan; line base and sides with baking paper, extending paper 5cm over edges.
2.Beat spread and sugar in medium bowl with electric mixer until changed to a paler colour. Beat in eggs, one at a time. Stir in milk, meal, sifted flour and cocoa, in two batches.
3.Spread mixture into pan; bake about 20 minutes. Stand cake in pan 10 minutes before turning, top-side up, onto wire rack to cool.
4.Meanwhile, for the fudge frosting, combine caster sugar, spread and the water in small saucepan; stir over low heat until sugar dissolves. Transfer to medium bowl; gradually stir in sifted icing sugar and cocoa until smooth. Cover; refrigerate 20 minutes. Beat frosting with electric mixer until spreadable.
5.Spread cold slice with frosting.