Step 1

Line a 20cm square brownie tin with baking paper. Tip all of the ingredients, except the salt, into a large pan and put over a low heat and stir until the sugar has melted. Turn up the heat and simmer for 15-20 minutes, stirring regularly to avoid the mixture catching, until it reaches 115C on a sugar thermometer.

Step 2

Remove from the heat and leave to cool for 5 minutes.

Step 3

Use a wooden spoon to beat the mixture for 5 minutes until it thickens and loses its shine – this will make the fudge beautifully crumbly.

Step 4

Tip into the tin, smooth out and push it right into the corners. Sprinkle with a little of the flaky sea salt. Leave at room temperature until completely firm.

Step 5

Tip out onto a chopping board and cut into 20 squares.