Thats the same caramel recipe i use for Caramel Slice mmmm..
the base is 1 cups brown suger, 1 cup self raising flour, 1 cup coconut and 125g melted butter. Mix and put into foil lined lamington tin, bake for 15 mins 180 degrees, melt the caramel the same as you have, put it on top of cooked base, cook for a further 10 minutes in oven, allow to cool then cover with melted dark chocolate and allow to set! mmmmmmm its the best caramel slice ever! DH eats it all in 2 days!!