Step 1

Grease and line the baking tin then preheat your oven to 180°C/Fan 170°C/356°F. Beat together the butter and sugar in a stand mixer (or large bowl with an electric hand whisk) until light and fluffy.

Step 2

Sift in the flour and add the salt. Mix until a dough forms.

Step 3

Press the dough evenly into the prepared tin then prick all over with a fork.

Step 4

Bake in the oven for 15-20 mins until just golden on top. Cool completely.

Step 5

Put all the ingredients into a large saucepan and set over a low/medium heat.

Step 6

Stir until everything has dissolved then bring to the boil. STIR OFTEN AND VIGOROUSLY. Once boiling, stir continuously so it doesn't catch and burn on the bottom/in the edges of the pan.

Step 7

When it becomes thick and is a light caramel colour (or hits 107°C/225ºF on a thermometer), take off the heat and keep stirring for a minute or two.

Step 8

Pour the caramel over the biscuit base, spread evenly and leave to cool completely.

Step 9

Break the chocolate into a glass bowl. To melt on the hob, set the bowl over a pan of barely simmering water and stir until melted. To melt in the microwave, heat in 10 second intervals stirring well each time until two thirds melted. Then stir well until completely melted.

Step 10

Pour the melted chocolate over the caramel and smooth out using the back of a wooden spoon. Allow to set at room temperature then cut into 12 slices.