Caramel shortbread, caramel squares, caramel slices, millionaire’s slice, chocolate caramel shortbread, Wellington squares…all names for the same thing. I have to admit that I have only really come to appreciate millionaire’s shortbread in the last few years. The first one I tried was from a British supermarket bakery and, while it wasn’t terrible, I also didn’t understand why exactly I would spend my sugar budget on exactly this. Millionaire’s shortbread?? Preposterous! But the homemade version is so very much better and truly enjoyable. I can even forgive the silly name. By the by I am not at all trying to design a nutritionally justifiable dessert here- it isn’t. But the version below nonetheless contains quite a bit less sugar by weight than the supermarket version I remember trying (45% vs 29% – ouch). And also fascinating. I went purely by taste so make of that what you will. But IMNSHO (in my not so humble opinion): one-nil for the home baker.
And if you wonder how this compares to some commercial chocolate bars: Mars and Twix are at 59% and 49% respectively (holy smokes).
Messing with the shortbread
Shortbread in principle is made of only three ingredients: flour, butter and sugar. It’s fairly classical to use a 3:2:1 ratio (and it’s easy to remember) but there are a lot of recipes that use slightly different quantities. I sometimes also add whole egg (when I make a pastry crust) or egg yolk (for Christmas biscuits) or cold water (when it gets too faffily crumbly) as well as ground nuts (which have quite a profound impact on the taste).
The genius idea for millionaire’s shortbread (with the chocolate on top) was first published in Scotland in the early 1970s followed by publications in Australia (for the first decade just with caramel which earned it the permanent name of caramel slice). While millionaire’s shortbread (with the chocolate) is nowadays hugely popular in Australia and New Zealand, I personally associate it very much with British cuisine.
My favorite recipe
As a ubiquitous baked good it’s not surprising that despite the similar final look there are a lot of variations in the recipe. That starts with the proportions: how tall and how much shortbread relative to caramel and chocolate? Then there is the shortbread itself: do you want it crumbly and short or more compact for neater cutting? How buttery should the caramel be (which is usually based on sweetened condensed milk) and how much do you mitigate the sweetness with salt? And finally the chocolate layer: dark or milk, crisp or soft?
Personally, I sacrifice neatness for a crumblier shortbread base. From there, my version is largely about balancing the sweetness of the caramel: enough salt, as little additional sugar as I can get away with, and dark 70% chocolate. Because I like the caramel soft-set, I top it with chocolate ganache rather than a solid layer of chocolate. The ganache stays soft enough that you can bite or cut through it without squashing the caramel out underneath. I also love adding nuts to the caramel layer for some crunch and a little more contrast.
I’d like to add one final note before getting to the recipe: having a thermometer is extremely helpful for this recipe. It is not necessary but judging when the caramel is done is not so easy: if it’s not cooked enough, it won’t solidify and will be runny, and if you take it too far it can become quite chewy. I like it just at the point where it’s neither. Don’t worry, it will still taste nice either way just not quite as good as when you hit the sweet spot.
Millionaire’s shortbread
Shortbread with layers of caramel and chocolate
Makes about 35 (4.5cm squares)
Ingredients
Shortbread layer
120 g sugar
240 g butter
360 g flour
decent pinch of salt
Caramel layer
one small can of sweetened condensed milk, just under 400g*
120 g butter
50 g dark brown sugar
2 tbsp golden syrup**
3/4 tsp salt
optional: 100 g nuts
Chocolate layer
200 g dark chocolate 70%
200 g cream ~30% fat
* the cans I can obtain here are either 370 g or 395 g (amusingly both made by the same major company, just produced for different markets). It really doesn’t matter that much when it comes to cooking the caramel.
**I don’t know where in the world golden syrup is available. It is there to inhibit the crystallisation of the sucrose in the caramel and also happens to support the flavor profile of the caramel. You can replace it with glucose syrup, agave syrup, honey (but use a neutralish one) or high fructose corn syrup.
Method
Make the shortbread dough
I cut the butter into small cubes and rub it into the flour/sugar/salt mixture. Once it’s somewhat distributed I bring it together into a dough and then stop immediately. Do not overknead it or it will become tough. If it doesn’t want to come together at all add a teaspoon of cold water at a time (it doesn’t take much). Rest it in the fridge for at least an hour or overnight.
Bake the shortbread
Preheat the oven to 180°C (350°F) conventional. Roll the dough out to the size of the pan. I like mine at a thickness of about 10mm. Line your tray with baking paper so that you can later lift it out, place the shortbread inside and do the final corrections (push the dough into all the corners), stab it everywhere with a fork so it doesn’t bubble up. If it got quite warm you can put the whole tray into the fridge or freezer for a few minutes, then bake for about 25-30 minutes. I bake mine until it’s golden brown in the middle and has brown edges and corners. But that’s really a matter of preference. Let it cool in the pan. Some recipes say that the caramel doesn’t stick if you let it cool but I have never found that with the way I cook the caramel.
Make the caramel
If you are adding nuts, scatter them over the shortbread base.
Place all ingredients for the caramel into a saucepan and heat at medium heat, stirring continuously. When it’s done it will have turned noticeably darker and become a lot more viscous than at the start. This process will probably take longer than you think. I use an infrared thermometer to measure the surface temperature and stop when I see about 112°C on the caramel itself. The reading fluctuates quite a bit as I stir, and once the caramel gets thick enough, the spatula can briefly expose the hotter bottom of the pan, so make sure you are actually measuring the caramel.
It’s normal for the temperature to stall during the process (fascinating thermodynamics I am sure) and you will notice a change at around 110°C where it gets quite a bit stickier. Pour it over the shortbread base immediately and then smooth it out. Don’t wait around at all, it will start setting right away. Let it cool to room temperature.
If you don’t have a thermometer: this quantity takes me about 25-30 minutes to cook. It’s done when it is noticeably darker and starts coming away from the sides and bottom of the pan as you stir.
Make the ganache
Chop the chocolate into relatively small chunks so it melts evenly. Heat the cream in a saucepan or microwave. Don’t let it come to a boil, there’s no need to get it that hot, and in my experience very hot cream makes the ganache more prone to splitting. If you have a thermometer: about 85°C is great and will melt all the chocolate. Pour the cream over the chocolate, cover, wait 30 seconds, then stir gently from the center (yes indeed stirring technique can influence the result here, chocolate is a diva!) until you have a (hopefully) smooth, glossy ganache (if not, there are ways of re-emulsifying even badly split ganache).
Pour over the caramel layer and spread it out evenly. Let it set for an hour or so before cutting.
Cut and decorate
You can decorate the shortbread with some white chocolate before the ganache sets, add decorations later or skip decorating altogether.
Lift the shortbread from the tray, it will not be that fragile. Cut it into small squares. You’ll get neater cuts if you use a hot knife and wipe it off after each cut. I also generally cut a few millimeters off the edge to straighten it (it makes the family happy, too). Add decorations to each square (for example some chopped nuts if you added them to the caramel). I like to serve mine in muffin paper cases but that is also optional.
Storage
The shortbread keeps well for several days in the fridge (let it warm up a little before eating). It also freezes quite well. If you freeze it, try to have as little air as possible inside the bag/container and on thawing, keep it in the bag. This way condensation will stay on the bag/container instead of on the shortbread itself.
Tray Size
I devised this recipe for a tray of about 31.5 cm x 22.5 cm (that way you end up with above number of squares: 7×5). I like this size because I can use a whole can of condensed milk. If you want to change the size, I found that the shortbread needs about 1g/cm² to come out at the thickness I like. So for example in a 20 cm square you’d need about 400 g total and about half the quantity of caramel and ganache (it will be marginally thinner but it’s not an exact science). My slice size comes out to just under 50 g which is similar to an average chocolate bar.
Time Management
Millionaire’s shortbread is not particularly difficult to make and quite tolerant to variations. It is a lengthy process overall, as there is quite a bit of waiting involved. I like to make my shortbread dough a day ahead and keep it in the fridge. You can also bake the shortbread the day before you want it. That way on the day of, it doesn’t take half a day (fine when you are near your kitchen but it can be annoying otherwise).
On the other hand, you get a lot of servings from a single tray because it’s so dense and intense.
Drop me a comment: do you know millionaire’s shortbread or have you made it before? If so, do you do things differently? And if not do you want to try it? (You definitely should.)