First of all, finely chop chocolate bars (note: nuts and caramel in chocolte bars, when you put in the freezer, becomes very hard to eat, so maybe you should choose a chocolate bar without them). Then whip up the cream and add condensed milk, pour chocolate and stir well.
Take a rectangular shaped baking tray, line with foil. Put biscuits one near another (if needed cut biscuits). All bottom has to be covered with biscuits layer. Then pour all cream - condensed milk and chocolate mass on the cookies, smooth with a spoon, and add another layer of biscuits. Carefully cover everything with foil and put in a freezer overnight. The next day you can enjoy this wonderful summer dessert!