Line a baking tray with baking paper and grease with butter (used 170 x 270 x 45mm tray to make nice big thick squares).
Melt butter and chocolate in a microwave 50-60 secs at a time - depending on your microwave you may repeat in 30 secs lots to avoid burning the mix.
Stir in condensed milk, add cocoa powder and coconut.
Crumb biscuits in a plastic bag with a rolling pin.
Stir into other ingredients, add sultanas and mix (it is quite firm to mix).
Press mixture into the slice dish and chill for about an hour.
Melt butter and Whittaker’s Creamy Caramel chocolate in the micro wave in 30-40 sec lots taking care not to burn the chocolate.
Mix in the icing sugar, leave to cool, do not worry if the icing looks greasy.
Once it is cool take a wooden spoon and mix the icing, it will turn the icing lighter in colour and give it a nice creamy texture.
Ice the slice and cut into squares.