Chocolate caramel bars with a salty sprinkle

There are a million ways to make these, but these are the best, bar none. Pecans, hazelnuts or almonds can stand in for the walnuts.

MAKES 14 BARS INGREDIENTS For the base

180g unsalted butter 220g plain flour 50g icing sugar

¼ tsp fine sea salt

For the caramel filling

380g sweetened condensed milk 50g dark muscovado (dark brown) sugar

100g dark corn syrup

100g unsalted butter

¼ tsp fine sea salt

1 vanilla pod, split and seeds scraped (or 1 tsp vanilla bean paste)

For the topping

40g walnuts

200g dark chocolate (60-70% cocoa solids)

15g unsalted butter

½ tsp sea salt flakes

METHOD

Preheat the oven to 160C/140C Fan/Gas 2. You will need a 23cm square, 5cm deep cake tin. Cut two pieces of baking paper as wide as the tin and long enough to cover the sides, with some excess paper overhanging. Spray the tin with cooking oil spray and lay one piece of paper across the base of the tin and up the sides, then place the second piece on top (to form a crosshatch). The paper will allow you to lift the slice out easily.

To make the base, melt the butter and leave to cool a little. Put the flour, icing sugar and salt in a heatproof mixing bowl and stir to combine. Pour the butter into the dry ingredients and mix with your hands to form a sticky paste. Press the mix into the prepared tin and smooth it out with an offset spatula.

Bake for 45 minutes until the base is a tan biscuity colour. If any bubbles form under the base while baking, just prick them with a skewer to gently deflate them.

Place the walnuts (for the topping) on a baking tray and toast them, at the same time as the base, for about 20 minutes, or until deep golden brown.

Clean the mixing bowl. Choose a saucepan that will allow you to nestle the bowl on top, without it touching the water below. Fill the pan with 5cm of water and bring to a gentle simmer on the stovetop.

To make the caramel filling, put all the filling ingredients in the cleaned bowl. Place the bowl on top of the pan of simmering water over a medium-low heat, stirring well occasionally, until the butter has fully melted and emulsified. The consistency should be thick and gloopy and the colour just a shade darker – this will take about 10 minutes.

Fish out the vanilla pod if