Measure out the sugar, butter and syrup into a deepish saucepan to allow the sauce room to bubble up.

Melt over a medium heat, serving to encourage the sugar and butter to dissolve into the syrup.

Turn heat up to high and bring up to a rolling boil for 5 minutes – do not leave the sauce unattended, boiling sugar will seriously burn you if it boils over.

Take off the heat completely then add the double cream, keeping hands out of the way incase it spits (it will only do this for a second or two as long as the sauce is off the heat). Stir well to combine.

Return to the heat and return to the boil for a mere minute or two. It will be runny at this stage – don’t worry, it gets all thickened and oozy when it cools down to room temperature.

Once again take off the heat and stir in the vanilla extract. You could add a splosh of booze at this point too – 2 tbsps is the most I would add of most liqueurs but do taste it once cooled and add more if you think you can take it.

Leave to stand for half an hour before pouring into a sterilised jar or bottle (I like to wait as it will be several hundreds of degrees when it comes off the heat as you are effectively making a caramel so I don’t like pouring directly into a glass vessel). Remember, I sterilise my glassware by putting through a very hot wash in the dishwasher.

When cold, refrigerate until needed – it will be very thick straight from the fridge so it may need to stand at room temp for a while before using, depending on how you are serving it.