Salted caramel & peanut butter billionaire’s slice

This popular shortbread bake is placed in a whole new league with the addition of an extra layer of indulgence plus a salted toffee topping

  • Prep:45 mins
    Cook:55 mins
    Plus 4 hrs chilling
  • More effort

Nutrition per serving

  • kcal 502
  • fat 31g
  • saturates 16g
  • carbs 48g
  • sugars 36g
  • fibre 1g
  • protein 8g
  • salt 0.7g


  • 225g butter, chopped into cubes, plus a little for greasing
  • 140g unsalted peanuts, toasted and cooled
  • 225g plain flour
  • 50g cornflour
  • 85g golden caster sugar
  • 140g butter
  • 225g smooth peanut butter
  • 140g icing sugar
  • 2 X 397g cans Carnation caramel
  • 1½ tsp flaky sea salt or ½ tsp fine sea salt
  • 3 x 100g bars dark chocolate, broken into small pieces
  • 140g soft dairy toffees
  • 3 tbsp milk
  • ½ tsp flaky sea salt


Cutting slices
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.Cooling your caramel
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.The right tool for the job
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.Creating a patterned topping
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.Getting the caramel layer right
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.


  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.

  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.

  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.

  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.

  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.

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