1.Preheat oven to 180°C (160°C fan-forced). Grease 1.25-litre (5 cup) and 2.25-litre (9 cup) pudding steamers. Make cake according to directions on packet, pour mixture into steamers until three-quarters full; bake smaller pudding about 35 minutes and larger pudding about 55 minutes. Stand cakes in steamers 5 minutes; turn onto wire rack to cool. Using serrated knife, level cake tops.
2.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.
3.Place small cake on board. Tint ½ of the butter cream with yellow colouring; spread all over cake for toadstool stem.
4.Position large cake on cardboard round, cut-side down. Position large cake on toadstool stem for toadstool cap. Tint remaining butter cream with pink colouring; spread all over cap.
5.Place pink Fruit Sticks, side by side, on flat surface; trim tops of sticks to make rounded door. Position on toadstool stem for door.
6.Split spearmint leaves in half through centre; slice halves into three pieces, as shown. Use centre pieces for stems and side pieces as leaves; position around toadstool stem. Position two mini heart lollies at top of each spearmint stem for flowers.
7.Cut yellow Fruit Stick into thin strips; using a little water, position on two large heart lollies; position on toadstool stem for windows.
8.Position six large heart lollies on board at front of toadstool for path. Decorate toadstool cap with cachous and remaining large heart lollies.
9.Using a little butter cream, attach large marshmallows on top of smaller marshmallows, sprinkle with sifted cocoa powder; position around toadstool. Decorate toadstool with fairy statues as desired.
Position the large cake on the small cake, then spread pink butter cream over toadstool cap. Split the spearmint leaves in half through the centre then slice the halves into three pieces.Note