I used a cake mould 24 cm x 7 cm
Line with plastic wrap and secure it with a rubber band. Easier to handle while filling
Melt chocolate and butter. I did in the microwave. You can do that in a double boiler as well. Leave to cool.
Beat the cream and fold in the chocolate mix. If you are using dark chocolate, you might want to add some icing sugar into the cream
Start stacking the cake. 1st layer biscuits
Add 1/4 of the chocolate mix and spread evenly. Then biscuit etc...
Cover and refrigerate for 4 hrs at leadt