Melt golden syrup gently in a pan and stir in butter. Once butter has melted, stir in biscuits, cocoa powder and cherries. Pile into basin and smooth down evenly with the back of a dampened metal spoon. Make sure the bottom is level as this will be the base of the cake.

Chill for 3 hours.

To cover the cake: microwave chocolate in a heatproof bowl on High, in 30 second bursts: it will take a couple of minutes or so in all. (Alternatively, melt chocolate in a bowl over a pan of barely simmering water: choose a bowl that will fit comfortably in the top of the saucepan but without the bottom touching the hot water.)

Stir in butter towards the end of melting time.

Loosen cake with a small palette knife and ease out of basin. Stand it, flat side down, on greaseproof paper. Remove cling film. Pour chocolate over the top smoothing it down the sides.

Position decorations before chocolate sets. Trim away excess chocolate from the bottom with a sharp knife and peel off the paper. Keep cool and covered until ready to serve.

Cut the cake at the table, in slices crossways rather than wedges, with a sharp knife dipped in boiling water.