Pour the sugar and milk into the pan. Heat until the sugar has dissolved. Add the condensed milk, butter, golden syrup and vanilla. On a low heat, stir until butter has melted and all combined.
Turn up the heat to medium and boil the mixture until it reaches 116°c (soft ball).
Remove from the heat and cool slightly (about 15 mins). Using a wooden spoon, beat the mixture until it thickens and appears dull in colour. This takes about 5-10 mins.
Pour into your tin and cool until it sets. Once it has set, carefully remove and cut into squares.
Notes
Storage - You can store your fudge in the fridge for 2-3 weeks. You can also store your fudge in a cool, dry place, in a sealed container. Freezing - I haven’t personally frozen my fudge but according to Nigella, you can freeze your fudge in a large block wrapped in cling film and foil, for around 6 weeks.