2. Bring to the boil then simmer for 10-15 minutes, stirring continuously and scraping the base of the pan. Take care while the mixture boils and during stirring as the fudge will be VERY hot! To test its ready drop a little of the mixture into a jug of ice-cold water. A soft ball of fudge should form. Or check with a sugar thermometer if you have one (approx 118°C).