To make the syrup, roughly chop the artichokes and feed them through a juicer. Allow the juice to stand still for an hour, and skim off any foam that settles on top.
Pass the juice through a double layer of damp muslin, and bring to the boil in a large stockpot.
Over a medium heat, allow the juice to reduce at a steady simmer, continuously skimming off any scum that rises to the surface, until you are left with a syrup roughly the colour of Marmite and a consistency similar to treacle when cooled.
Combine the artichoke syrup, glucose and whipping cream in a small stock pot and bring slowly to the boil, stirring to combine. When the mixture boils, reduce to a medium simmer and cook until it reads 100°C on a sugar thermometer.
Then turn the heat down as low as it will go, and cook until the mixture reaches 112°C, stirring gently but frequently. At this point, remove the pan from the heat and immediately beat in the butter while the mixture is still hot, followed by the salt and vinegar.
Scrape the warm mixture into a deep roasting tin lined with baking parchment. Once the fudge is cool to the touch, transfer the tin to the freezer to set hard.
Remove from the freezer and use the baking parchment to lift the fudge out onto a chopping board. After 10 minutes or so at room temperature, use a large knife heated in hot water to cut the fudge first into 2cm wide strips, and then into squares.
Line up the fudge pieces on fresh parchment and return to the freezer for an hour. Melt the chocolate in a heatproof bowl set over a small pan of barely simmering water.
Using a fork, plunge the fudge squares one at a time into the chocolate to cover them completely, then knock off the excess chocolate by tapping the fork against the edge of the bowl. Carefully replace the fudge in rows on the baking parchment and return to the freezer to set the chocolate.
To serve, remove the fudge from the freezer, trim any splattered chocolate edges with a paring knife, and allow to thaw in the fridge for 30 minutes.