Preheat the oven to 160°C and grease a 20cm square tin with parchment paper.
Beat the sponge ingredients until smooth and transfer to the tin.
Bake for 40 minutes until a skewer comes out clean.
Cool in the tin for 10 minutes then chill in the fridge until cold.
Beat the butter and icing sugar until smooth to make buttercream.
Place 100g of buttercream in a piping bag and chill slightly.
Sieve heated apricot jam into a bowl.
Brush the top of the chilled cake with the jam.
Roll marzipan thinly, cover the cake, and chill again.
Cut the cake into twenty-five 4cm squares with straight edges.
Coat cake sides with buttercream and pipe a blob on top before chilling for 20 minutes.
Mix fondant cubes with a splash of water in a mixer until liquid.
Add food colouring and flavouring to the icing to taste.
Melt the dark chocolate and place it in a piping bag.
Place a cake square onto a fork.
Dip each square into the fondant and set on a cooling rack.
Allow the fondant to set at room temperature to maintain shine.
Drizzle the cakes with melted chocolate in a zig-zag pattern.
Let the chocolate set before serving.