After doing some research, I've found that these can also be called Caramel Shortbread or Millionaire's Slice - whatever you want to call them, they are certainly enticing and very decadent. The bottom layer is simply flour, sugar, a dash of salt and soft butter that is given some love with your fingers until crumbly - all you need to do is press it into a tin and it bakes into a thick and buttery shortbread crust. While waiting for the crust to cool, you throw together a caramel - however, this one is one not to be afraid of and is fairly no-fail. A bit of butter, sweet muscovado sugar and sweetened condensed milk (did I mention this was rich?) are brought to a boil and then left to simmer until the milk thickens and turns a light caramel color. The most important step with this process is to keep the mixture moving - you want to constantly stir, otherwise the bottom will begin to scorch and give this an off flavor. Depending on how high your simmer is, this could take anywhere from 5-15 minutes - you will definitely be able to see when it is done as it gets pretty thick. Once this fantastic mixture is poured over the crust, it needs time to set - you can rush this by placing it in the refrigerator, but we just left ours on the counter and it was good to go in about 30 minutes.
To push this over the top, alternate lines of bittersweet chocolate and milk chocolate are poured on the caramel layer. Dollops of white chocolate are scattered and with the use of a thick skewer, we gently swirled all the chocolate together. Don't do too much as you don't want to muddle the colors - you want to do it just enough so every piece will have a bit of each kind of chocolate on top.
We cut ours into 30 pieces, but you could even cut them a little smaller and still be completely satisfied. The solid buttery base was a perfect way to show off the luscious caramel layer (though, it was almost more like dulce de leche to me with using the sweetened condensed milk). The trio of chocolates on top make for wonderful eye candy and finish this treat with a final mouthwatering layer of sweetness.
Marbled Caramel Chocolate Bars