For the base

For the peanut butter layer

For the salted caramel layer

For the chocolate-toffee topping


  • STEP 1

    Heat oven to 180C/160C fan/gas 4. Grease and line a 20 x 30cm rectangular cake tin with baking parchment – the best way to do this is with 2 long strips of parchment. Put the ingredients for the base in a food processor and blitz until it starts to clump together – don’t worry if the peanuts are still a little chunky, they will add a lovely texture. Tip onto your work surface and knead briefly to bring together as a dough. Press the dough into the base of your tin in an even layer. Bake for 25 mins until golden, then set aside to cool.

  • STEP 2

    To make the peanut butter layer, melt the butter and peanut butter in a small pan and mix until smooth. Sieve the icing sugar into a bowl, then pour in the hot butter mixture and stir to combine. While the mixture is still warm, pour over the base and smooth out with a spatula. Chill for 2 hrs until set.

  • STEP 3

    To make the caramel layer, put the caramel and salt in a pan, bring up to the boil and simmer vigorously for 2-3 mins, whisking continuously, until the colour darkens a shade or two and the caramel thickens slightly. Leave the caramel to cool for 20 mins (see tips, below). Once cooled, pour it over the peanut butter layer and return to the fridge for a further 2 hrs.

  • STEP 4

    Melt the chocolate in a heatproof bowl set over a pan of barely simmering water. Meanwhile, put the toffees and the milk in a small saucepan and gently heat. They will clump together and struggle to melt at first, but keep heating and eventually they will turn into a runny toffee sauce.

  • STEP 5

    Remove the tin from the fridge and pour the chocolate over the salted caramel layer, tipping the tin to spread the chocolate over the surface. Use a spoon to quickly drizzle the caramel over the chocolate in a thin loopy pattern (or see tip, below). If the toffee starts to get too thick, add a splash more milk or cream and pop it back on the heat until runny. Sprinkle over the sea salt flakes and put the tin back in the fridge to chill for 2 hrs before slicing.


To cut into pieces without shattering the

chocolate layer, remove the billionaire’s

slice from the fridge 15 minutes before

slicing. Use a sharp knife to score the

surface into sections while still in the tin.

Remove from the tin, then cut through,

using the scored lines as a guide.


You don’t want your caramel to be

piping hot when it’s poured over the

peanut butter layer, as it will melt the

butter and make the layers separate.

So cool the caramel at room temperature

for 20 minutes first, or pour it into a jug

and stand in a sink of cold water for

five minutes, stirring continuously.


We used a 20 x 30cm tin with a slide-out

bottom. This makes it much easier to

remove the billionaire’s slice from the tin

without cracking the top.


To create the perfect swirly toffee

topping, invest in a plastic squeezy bottle

with a small round nozzle. Leave the

caramel to cool for five minutes before

pouring it into the bottle, then quickly

create the loopy pattern.


To check the caramel has thickened

enough, you can do the jam test. Spoon

a little of the caramel onto a plate and pop

it in the fridge for five minutes. When you

remove it, the caramel should be softly set

and have a similar texture to softened

butter. If it is still runny, return the pan to

the heat and boil for another minute or

two, then check again.

Goes well with


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