Millionaire’s Shortbread, Caramel Slice, Caramel Shortcake, Millionaire’s Shortbread Bars or Caramel Squares… whatever you want to call it, this sweet, sticky traybake is just deliciously decadent!
Made with layers of buttery shortbread, rich soft caramel, topped with chocolate, it’s basically like a homemade Twix bar, but even better!
I’ve been eating variations of this delicious treat my whole life. Millionaire’s Shortbread is often called Caramel Slice in New Zealand, and the ingredients of the base layer can differ slightly.
But since we’re here to make Scottish food, I wanted to make a traditional Millionaire’s Shortbread, using our three-ingredient shortbread recipe as the base layer, before topping it with easy to make caramel and dark chocolate decadence.
Yes, it’s rich, but it is shortbread for Millionaire’s after all!
Pin for later!
Where does Millionaire’s Shortbread come from?
We’ve previously talked about how shortbread comes from Scotland and is considered a classic Scottish food, but the origin of the jazzed-up version is a little more in doubt.
While the name “Millionaire’s Shortbread” seems to have originated in Scotland there’s some debate about the actual recipe. Some cite the Australian Women’s Weekly as being the source of “Caramel Shortbread” but there have been so many variations and names that it’s hard to keep track!
We’ve made it in the most traditional way possible, without any fancy variations. Because it’s delicious just as it is! So let’s just call it Scottish, and move on to the making of the treat, shall we?
Things you’ll need to make Scottish Millionaire’s Shortbread
9-inch square baking tin: This is tin you’ll need to give you the right thickness for all of the layers you’re making. If you only have a larger tin then the layers will be thinner.
Baking paper: It’s useful to put a large sheet of baking paper in the tin with some overhang, rather than greasing the tin directly, as then you can lift the slice out to cut it into squares.
Ingredients for Millionaire’s Shortbread
The different textures of the three layers are what makes this Scottish Millionaire’s Shortbread so appealing. It’s actually relatively easy to make, you just need to individually make each layer and wait for them to cool and set in-between. I made it over the course of a day, in between childcare!
You can use the same shortbread recipe as the one we used for our traditional Scottish Petticoat Tails Shortbread. It’s a 3:2:1 ratio recipe with three parts flour, two parts butter, and one part sugar.
- 300 grams plain flour (2 cups)
- 200 grams butter (1 cup)
- 100 grams caster sugar (1/2 cup)
- Pinch of salt (optional)
Some variations of Caramel Squares or Caramel Slice add coconut into the base layer or use crushed biscuits instead (sometimes even crushed shortbread with extra butter!) but it’s so easy to make your own shortbread and we think traditional shortbread is a much better tasting base.
Caramel is often considered to be something that’s hard to make and that requires a candy/sugar thermometer, but that’s not the case here. By using sweetened condensed milk it simplifies the recipe and helps it to set.
You want the caramel to be soft, but not chewy, and definitely not runny.
- 100 grams butter (1/2 cup)
- 85 grams brown sugar (3/4 cup)
- 2x 397g tins of sweetened condensed milk
Millionaire’s Shortbread is topped with plain chocolate rather than a softer ganache, to add texture.
We prefer using dark chocolate, but some Millionaire’s Shortbread recipes call for milk chocolate. The reason we like dark chocolate is the bitterness helps to cut into the sweetness a little and balance it out. However, if you don’t particularly like dark chocolate you may prefer to try it with milk chocolate, or a mix.
- 300g dark chocolate
- 1 tablespoon oil
We just used store brand dark cooking chocolate and it turned out great. No need to use fancy dark chocolate for this (despite the name!).
Using a tablespoon of oil helps with cutting the slice afterwards. We used olive oil because that’s what was to hand but you can use vegetable oil or coconut oil, or omit it altogether.
How to Make Millionaire’s Shortbread Step-by-step
I’ve broken down how to make Millionaire’s Shortbread step-by-step here, but you can skip straight through to the recipe card for the full list of ingredients and simplified method all together at the end of the post.
Allow yourself plenty of time to make this because you’ll need to allow each layer to cool before adding the next one.
The first step is making the biscuit layer. You need a firm biscuit to hold all that caramel and chocolate!
You can already find a full step-by-step guide to making shortbread for our Shortbread Petticoat Tails here, but I’ve simplified it below as well.
Start by creaming the butter. Make sure the butter is room temperature before starting, to make it easier to cream. Add the sugar until it’s just dissolved and combined. I use an electric whisk for this process but it is possible to do by hand with a wooden spoon.
Next, add the flour, and bring together until it forms clumps. You might need to get your fingertips involved! Try not to work the mixture too much with your hands though.
Don’t worry too much about making the mixture form a full ball of dough like you usually would with shortbread. Instead, you can just tip it into your baking-paper lined cake tin and press it down evenly to form the first layer.
Prick the shortbread all over with a fork and then bake in the oven for approximately 30 minutes at 160C/325F until just going lightly golden brown.
You’ll want to allow the shortbread to cool before adding the caramel layer, so I usually wait until it’s been baked to start making it.
Add the butter and sugar to a saucepan and allow to melt together and dissolve, while stirring. Pour in the two tins of condensed milk. You’ll need to stir the caramel mixture constantly to stop it burning to the bottom of the pan.
Bring it to the boil initially for a couple of minutes before turning the temperature down to simmer for around 10-15 minutes. It will start to darken and thicken up and that’s how you’ll know it’s ready.
Pour the caramel over the shortbread layer, taking care to make sure it’s evenly spread. You can use the back of a spoon, shake the tin slightly from side to side, or lift and allow it to bang down onto the kitchen surface (although take care it’s not from too high! You don’t want to break the shortbread).
The caramel should start to set as it cools. I would wait at least one hour before moving on to the chocolate layer. All this waiting will be helping to build the anticipation until you get to eat!
The final layer of chocolate can be done in the microwave or in a bowl over a pan of hot water. I find the microwave much easier!
Break the chocolate up if using whole bars and blast in the microwave for 30 seconds at a time, taking care to take it out and stir in between. You can add the oil when it’s about half melted.
Pour the chocolate onto the cooled caramel layer and repeat the above steps to make sure it’s evenly spread.
The chocolate layer always works best when cooled at room temperature, despite how tempting it is to put it in the fridge at this point so you can eat it sooner!
We had to wait quite a while for it to set but it was worth the wait.
How do you cut Millionaire’s Shortbread?
The difficulty in cutting Millionaire’s Shortbread comes from the hard chocolate later. You don’t want it to crack, or to press down and have the caramel all ooze out the sides.
Keep a close eye on it and cut squares when the chocolate not fully set, or dip a knife in hot water then dry before cutting to help keep the squares together.
- 300g plain flour (2 cups)
- 200g butter (1 cup)
- 100g caster sugar (1/2 cup)
- Pinch of salt (optional)
- 100g butter (1/2 cup)
- 85g light brown sugar (3/4 cup)
- 2x 397g tins of sweetened condensed milk
- 300g dark chocolate
- Tbsp oil* See notes
- Turn on oven to 180C/350F
- Place a layer of baking paper into a 9-inch square baking tin with some overhang to allow you to lift it out later
- Cream butter and sugar together until sugar is just dissolved.
- Add flour (and salt if using) and mix together to form clumps, using fingertips if necessary
- Tip into the baking tin and press out evenly
- Bake for 25-30 minutes until lightly golden
- Remove and allow to cool
- Melt butter and sugar together in a saucepan over a medium heat
- Add the two tins of condensed milk
- Bring to the boil, stirring constantly and allow to boil for 1-2 minutes
- Turn down to a simmer and continue to stir for 10-15 minutes until the mixture has thickened and darkened
- Tip over the shortbread layer, using the back of a spoon to make the mixture smooth, or shake the tin from side to side
- Allow to cool and set
This can be done in the microwave or a bowl over a pan of hot water on the stovetop.
For the microwave, melt the chocolate in short 30 second blasts, stirring in between each one. Add the oil when the chocolate is half melted.
Pour the chocolate over the cooled caramel and shake the tin from side to side so that it is evenly spread.
We used olive oil but you can use vegetable or coconut oil as well, or omit altogether. It is used to help cut the Millionaire's Shortbread more easily. You can do so by scouring when the chocolate is almost set, or by using a knife with the blade heated in hot water but dried before cutting.
Amount Per Serving: Calories: 280Total Fat: 16gSaturated Fat: 9gTrans Fat: 0gUnsaturated Fat: 5gCholesterol: 32mgSodium: 107mgCarbohydrates: 32gFiber: 1gSugar: 22gProtein: 3g