Preheat oven to 130°C/260°F. Grease and flour deep 23cm (9-inch) square cake pan and deep 15cm (6-inch) round cake pan.

Make cake according to directions on packet. Pour enough mixture into each pan to fill to three-quarters. Use any leftover mixture to make cupcakes for another occasion. Bake cakes about 1¼ hours. Stand cakes in pans 5 minutes; turn, top-side up, onto wire racks to cool

Meanwhile, to make butter cream, beat butter in small bowl with electric mixer until as white as possible. Beat in sifted icing sugar and milk, in two batches

Tint butter cream pink. Level cake tops, turn square cake, cut-side down onto 36cm (14-inch) square prepared cake board (allowing space for drawbridge); secure with a little butter cream.

Using one of the biscuits as a guide, cut rounds out of each corner of square cake with a small serrated knife

Secure round cake to square cake with a little butter cream; cover whole cake with butter cream. Stack six biscuits, joining each with butter cream, in each of the cut-out corners of the cake.

Using scissors, trim waffle cones to sit flat, position one on each corner and one on the top of the castle to make towers

Remove candy rings from bracelets, position four rings on each lollipop stick, gently push lollipops into each tower; position flags. Position sugar cubes using picture as a guide

Using scissors, trim wafers into shapes for windows, door and drawbridge; position on cake.

To make chains for drawbridge: cut 2 bamboo skewers to about 12cm in length. Position a Mallow Bake at the end of each skewer to hold the candy rings in position. Slide the candy rings onto the skewers; using picture as a guide, position on cake.