Chocolate Fingers, the Bar to Beat All Bars! (No Bake)

"This recipe has been in my family recipe book for more than 20 years... I can't remember if I got it off a friend or out of the newspaper or if it was from my mother.... it's an "always been there" recipe and if you double it you can keep a whole school class full of kids very happy. It disappears rather quickly around adults too :) This recipe is different from many other ones with condensed milk, coconut etc because it contains sultanas but no nuts. It's easy to make and stores well in an airtight container... so can be made in advance, handy when party planning. The icing can be made with chocolate OR cocoa powder or a little of both, works well all ways. PLEASE NOTE: this single batch of the recipe calls for HALF a can of condensed milk... our cans are 397 grams = 14 oz) so you will only need 7 oz. DO melt the butter completely before adding the condensed milk, otherwise you will have lumps of butter that are difficult to melt, and do keep the heat very low for the condensed milk mixture because it scorches easily. The finished bar /slice is also nicer if you leave the cookie crumbs fairly chunky and *not* a fine dust. ZWT REGION: New Zealand...."