I remember being in primary school and checking a baking book out of the library – once home I photocopied a bunch of recipes from it, one of which was for Millionaire’s shortbread (also known as caramel slice in some parts of the world). It was something I’d had the shop-bought version of (in those clamshell plastic tubs!) and LOVED but had never made before. Now that I had a recipe for a homemade version there was no turning back! My brother and I made it many times – it’s such an easy bake and really requires minimal effort. They’re also VERY rich (hence why they’re called ‘Millionaire’s shortbread) so I often only need one square to satisfy my sweet tooth.
Recipes for millionaire’s shortbread are usually pretty similar. I think the BBC /Nigella /Jamie Oliver versions all have the same components with very similar ingredients. A shortbread base, a caramel filling made using sweetened condensed milk from a tin, and a plain chocolate topping. Some versions use golden syrup in the filling (I make it without) to prevent the sugar from crystallising. I’ve tweaked the recipe here and there to make my best version which is what I’m posting today!
I’ve even got a lil video below so you can see step-by-step how to make it 🙂
How to make crumbly shortbread for the base:
My shortbread base includes ground almonds – they are optional as you can swap out for rice flour/plain flour, but they do help the shortbread base stay nice and crumbly. They also have a nice buttery note to them and, unlike rice flour, don’t add a gritty texture.
Can you make millionaire’s shortbread without condensed milk?
Usually the caramel is made with sweetened condensed milk cooked with sugar and butter until it caramelises and thickens. For my filling, I simply swap the condensed milk for tinned carnation caramel (a.k.a. dulce de leche) instead. This tinned caramel is actually made from sweetened condensed milk so it’s essentially the same thing but it’s pre-caramelised for you! I like using the pre-made carnation caramel instead of sweetened condensed milk as I think it (1) has a deeper flavour, (2) it doesn’t seem to burn as easily as plain sweetened condensed milk does (3) it seems that post-pandemic, sweetened condensed milk is often out of stock in my supermarket whereas the carnation caramel is plentiful! You can’t just use the caramel straight from the tin though as it won’t set properly so you do have to cook it with sugar & butter to get it to thicken up.
All that said, you can use sweetened condensed milk here instead of the tinned caramel if that’s all you can get. It will work just as well but you might have to cook it for longer to get the right consistency AND you’ll have to be more careful that it doesn’t burn.
How do you thicken the caramel?
The caramel & butter & sugar are cooked on the stove in a pot, stirring often to melt everything together and thicken things up. This happens because the heat causes the mixture to boil, releasing some of the water in the ingredients as steam. It takes around 7 to 10 minutes of cooking over a medium-low heat to get this effect. You have to be careful as you thicken the mixture though as the high sugar content means it’s likely to burn easily – this can be prevented by stirring often (and scraping the base and corners of the pan with a silicone spatula). Bare in mind that the caramel will also thicken & harden as it cools in the fridge so it will seem thinner when it’s hot.
Why is my caramel too thin?
The caramel will be too thin if you haven’t cooked it for long enough on the stove. To test whether you’ve cooked the caramel for long enough, I like to use a simple trick. I place a small plate in the freezer before I start making the caramel. Once the caramel is looking darker and thicker than before I remove the plate from the freezer and place a little blob of hot caramel onto it. I set the plate aside for a minute or two so the caramel can cool down. Once cool to the touch, I run my finger through the blob. If the caramel is correctly cooked, the line will remain in the caramel. If it needs to be cooked for longer, the caramel will start to run back together, filling in the line.
What type of chocolate should you use?
I quite like a dark chocolate for the topping as it really helps to balance out the sweetness of the other ingredients. A 70% or even 80% are great but go with what you know you like. For this batch, I swirled on a bit of white chocolate into the dark for decoration but that’s totally optional.
How to cut Millionaire’s shortbread neatly:
I have a kitchen blowtorch which I use to gently warm a sharp knife before cutting into the shortbread. This helps to create the neatest edge as it melts through the chocolate and caramel as you apply pressure, meaning the chocolate wont crack or cause the caramel to squash out! If you don’t want to mess around with a blowtorch, you can fill a jug with boiling water and pop your knife blade in there for a minute or so. Wipe the blade dry before using it as it’ll be wet! With both these methods be careful not to touch the blade while you cut as it’ll be very hot. Also, wipe the blade with a piece of kitchen roll between cuts to ensure the knife is clean & dry.
Can you put it in the fridge or freezer?
I recommend storing the cut squares in an airtight container in the fridge. It’ll ensure they keep for longer (up to 1 week!) and will stop the chocolate/caramel getting all melty. You can freeze these too – cut them into squares and pop into a resealable sandwich bag for up to 1 month. Let them defrost at room temp before eating.
Other bar recipes:
- 50g (1/2 cup) ground almonds
- 60g (1/4 cup) caster sugar or granulated sugar
- 200g (1 2/3 cup) plain white flour
- pinch of salt
- 150g (1/2 cup + 3 tbsp) unsalted butter, cold, cubed
- 1 (397g/14 ounce) tin carnation caramel (dulce de leche) OR sweetened condensed milk
- 100g (7 tbsp) unsalted butter
- 100g (1/2 cup) caster sugar or granulated sugar
- pinch of salt
- 150g (5.3 ounces) dark chocolate (I used a 70%), broken into chunks
- 50g (1.8 ounces) white chocolate, broken into chunks
For the shortbread:
- Preheat the oven to 180C fan. Line an 8- or 9-inch square baking tin with a sling of baking paper.
- In a large bowl place all of the shortbread ingredients. Rub the butter into the dry ingredients using your fingertips until crumbly. Knead a few times in the bowl to form a cohesive dough.
- Crumble up the dough into the lined tin. Use your hands to flatten into an even layer then use the back of a spoon to smooth out.
- Bake for 25-30 minutes until golden brown on top.
For the caramel:
- Place the caramel (or dulce de leche or sweetened condensed milk) into a medium pot with the butter, sugar and salt.
- Heat on medium, stirring often, until the butter has melted. Lower the heat to medium-low and continue to cook, stirring often, for 7-10 minutes until the caramel has thickened and darkened. (NB: if using sweetened condensed milk here, it may be necessary to cook for slightly longer to get it to the right colour. You will also have to watch the caramel more closely & stir more often as it is more likely to catch and burn).
- Pour the hot caramel over the baked shortbread and spread out into an even layer (an offset spatula works well but you can also use the back of a spoon). Chill for 10 minutes so the caramel can firm up as you prep the chocolate.
For the chocolate top:
- Place the dark chocolate and white chocolate into two separate, heatproof bowls. Place each bowl over a pan of simmering water on the stove, making sure the bottom of the bowl isn't touching the water. Stir occasionally until melted and then remove the bowls from the pans of water.
- Pour most of the melted dark chocolate over the cooled caramel. Spread out into an even layer and then rap the whole tray against the work surface a few times to help the chocolate settle into a smooth layer.
- Dollops random blobs and swirls of white chocolate over the dark chocolate. Dollop the remaining dark chocolate on top in random spots. Rap the whole tray against the work surface again a few times to help the chocolate settle. Use a toothpick to swirl the dark and white chocolate together to create a marbled pattern.
- Chill for 10-20 minutes until set.
Remove from tin & cut:
- To remove from the tin you can either use a kitchen blowtorch to briefly warm the edges of the tin (only if the tin is metal!) which will help melt the chocolate and caramel at the very edges so you can lift out the whole thing with the sling. The other method is to dip a butter knife into boiling water, wipe it dry, then run it around the inside edge of the tin to release the chocolate from the edge of the tin.
- Cut into 16 squares using a hot knife (warmed either by running a blowtorch over the blade or by dipping the blade into boiling water & wiping dry) making sure you clean the blade between cuts for the neatest edges.
- Store cut bars in an airtight container. I recommend keeping them in the fridge (especially if your kitchen is warm!) for up to 1 week. They're delicious cold from the fridge or at room temp.