1.Preheat oven to 180°C/350°F; grease 1.75-litre (7-cup) pudding steamer.
2.Make cakes according to directions on packets. Pour mixture into steamer; bake about 50 minutes. Stand cake in steamer 5 minutes before turning onto wire rack to cool.
3.To make butter cream, beat butter until white as possible, gradually beat in half the sifted icing sugar then milk, then remaining icing sugar. Beat until smooth.
4.Level bottom of cake; secure cake, cut-side down, on 45cm (18-inch) square cake board with a little butter cream.
5.Knead icing on surface dusted with a little sifted icing sugar until icing loses its stickiness. Roll icing on surface dusted with sifted icing sugar into a 3mm thickness. Cut hat peak from icing; mould around cake.
6.Tint butter cream blue; spread all over cake and hat peak.
7.Tint remaining ready-made icing yellow; roll three-quarters of the icing into a thick rope shape. Position around edge of hat.
8.Roll remaining icing on surface dusted with sifted icing sugar into a 3mm thickness; cut out name plaque. Position name and desired candy cake decorations on plaque using a little water; position plaque on hat.
9.Place assorted toy tools around cake.
Build it and they will come…and eat it with gusto. The toy tools are readily available from most toy stores. White icing is also known as fondant (it’s the traditional icing used on wedding cakes). It is available in packets from the supermarket and cake decorating shops.