1.Preheat oven to 150°C/300°F. Grease and flour 14cm x 21cm (5½-inch x 8½-inch) loaf pan.
2.Make cakes according to directions on packets. Pour mixture into pan; bake about 1 hour. Stand cake in pan 5 minutes before turning, top-side up, onto wire rack to cool.
3.To make butter cream, beat the butter (and any flavouring, if using) in a small narrow bowl with an electric mixer until the butter is as white as possible (this will result in a whiter butter cream which will give you better results if colouring it). Gradually beat in half the sifted icing sugar then the milk, then the remaining icing sugar. Beat until the butter cream is smooth and spreadable. Keep scraping down the side of the bowl during beating.
4.Level top of cake; reserve cake scraps. Turn cake, cut-side down, onto surface. Make a shallow cut into cake at one end to a depth of about 5cm (2 inches), for the windscreen; reserve scrap of cake. Secure cake scrap on cake board with a little butter cream to elevate the fire engine slightly off the board (so you can later fit the wheels). Position cake on cake scrap; secure with a little butter cream.
5.Tint butter cream red; spread all over cake.
6.Knead ready-made icing on surface dusted with a little sifted icing sugar until icing loses its stickiness. Roll one-quarter of the icing on surface dusted with sifted icing sugar into a 3mm (⅛-inch) thickness. Using patterns from pattern sheet, cut out windscreen, windows and number plate. Press windscreen and windows onto cake.
7.Tint remaining icing grey using black colouring; roll on surface dusted with a little sifted icing sugar into a 3mm (⅛-inch) thickness. Cut out one 8cm (3¼-inch) square and two 3cm x 7cm (1¼-inch x 2¾-inch) rectangles. Using the side of a small metal spatula or ruler, make indents, 5mm (¼-inch) apart, on rectangles to represent roller doors.
8.Position square on top of fire engine and press roller doors onto sides. Position licorice along sides of fire engine. Shape remaining grey icing into two bumper bars; position on fire engine.
9.Use writing icing to write child’s name on number plate. Attach to bumper with a little butter cream. Using a little butter cream, attach biscuits to fire engine for wheels. Use Smarties to make sirens and lights. Trim mocha sticks to make a ladder for the roof.
Equipment: 14cm x 21cm (5½-inch x 8½-inch) loaf pan; 25cm x 30cm (10-inch x 12-inch) rectangular cake board. Make sure you use good quality food colouring to make the butter cream a strong red. The fire engine can be completed up to two days before the party. Make windscreen wipers from scraps of licorice.