Grease and line a 22/23cm spring form deep tin.

In a double boiler over a low heat put the chocolate and butter to melt together.

In a food processor blitz the biscuits together. They do not need to be fine and should have a few pea size pieces left.

In a large mixing bowl Mix together the Maltesers, Marshmallows and biscuits together and then pour into this the sweetened condensed milk. Mix very well.

Once the chocolate and butter has melted add this to the biscuit mixture. A lot of muscle is required here. It may initially seem there is not enough chocolate to bind the mixture but mix hard until the chocolate has been distributed evenly.

Put the mixture into a lined tin. Don't put too much in at a time. I suggest starting with a layer about 2 inches tall and with a potato masher press it down. Repeat this until all the mixture has been used up.

Layer a circle of greaseproof paper on the top and push down to flatten the top.

Refrigerate for 4 hours until the cake is hardened.

Turn out and eat. Or cover in royal icing to make it last that much longer.