My mom used to make this caramel slice when my siblings and I were growing up, it's still a family favourite now.
I double it when I make it, but have written the single batch recipe.
It's in metric but I've checked how to convert it so will be both:
1 395gm/ 13.93OZ can Sweetened condense milk (name brand seems to work better then store brand but that could just be here).
2 tablespoons golden syrup.
130/ 4.58OZ Butter
180gms plain biscuits/4OZ plain cookies
150gm/5.2OZ cooking chocolate.
Biscuit base: Melt 90gm/ 3.17oz of butter and crush the biscuits.
Mix the butter with the crushed biscuits and press the mixture into a pan. place in fridge to set.
Place condensed milk, golden syrup and left over butter in pan over medium heat.
Cook stirring constantly (mine always looks like a lumpy odd mess but its meant to a this point) 5-8 mins or until it thickens and becomes a light caramel colour (or the way I do it is, place half a tea spoon of it on a plate tip upside down and if it doesn't move its ready).
Take off heat, pour on to biscuit base spread evenly.
Allow to cool for about 30mins.
Melt the chocolate in a bowl, I use the microwave as its quicker.
pour melted chocolate over the caramel.
Place all in fridge until chocolate has set.