In a medium saucepan, add the sugar and water. Heat over medium-low heat, stirring gently until the sugar dissolves.

Stop stirring and increase the heat to medium. Let the sugar bubble and turn a deep amber colour. This takes about 5-7 minutes. Keep a close eye on it, as it can burn quickly!

Carefully whisk in the butter, a few pieces at a time. It will bubble up, so be careful!

Slowly pour in the double cream, whisking continuously until smooth. If adding salt or vanilla, stir it in now.

Let the caramel cool for 10-15 minutes, then transfer to a jar. It will thicken as it cools. Store in the fridge for up to two weeks and gently reheat before using.