Grease a 20cm cake tin. Place all the ingredients except the vanilla into a medium, heavy based saucepan. Warm over a gentle heat until the sugar has dissolved, about 10-15 mins.
Bring to a gentle boil and cook for about 10-15 minutes, until it reaches the soft ball stage (120°C). Remove from the heat and add the vanilla. Cool for 5 minutes then beat using an electric mixer until the fudge is creamy and thick and has lost its gloss (approx. 10 minutes).
Pour into prepared tin, score the top and cut into pieces when set.
Tip: Cut two sheets of baking paper the width of the tin, criss-cross the paper to line the tin making sure the sheets are long enough to extend over the sides. Use the paper to lift the fudge out of the tin once it has set.
Special thanks to Jo Seagar for use of the Best Ever recipe.