Millionaire's shortbread

I tried a new recipe from the cookbook Baked. I've had some success with recipes from these authors, and I wanted to try something other than cookies or a cake so I went for millionaire's shortbread. It's described as like a Twix. There's a layer of shortbread on the bottom, then a layer of caramel, then a layer of chocolate.

It was very good and very rich, but I won't be making it again. I had a bit of trouble with the caramel...You make it with two cans of sweetened condensed milk. The faster way is to cook it in the microwave at low power in short bursts, stirring in between. That still takes about a half hour, but I was going to try it. The first time I opened it to stir, it had exploded! There was a dome of sweetened condensed milk over the bowl, and it had spilled out all over the microwave. OH NOOOOOOO!

I switched to the stovetop method, which unfortunately takes two hours of sitting by the stove, occasionally stirring and making sure the boiling water under the bowl with the caramel doesn't evaporate completely. It's a shame that part takes so long because this is really very easy and it's very good. Final verdict: success taste-wise but takes too long to make again.