blue food colouring
6 tbsp good-quality strawberry jam
175g/6oz caster sugar
300²µ/10½ icing sugar
2-3 tbsp icing sugar, for dusting
500g/1lb 2oz white, ready-made marzipan
175g/6oz self-raising flour
½ tsp vanilla extract
175g/6oz softened butter, plus extra for greasing
150²µ/5¼´Ç³ú butter, softened
3 free-range eggs