Meanwhile, whilst waiting for the cake to cool prepare the salted caramel by adding butter, golden syrup and sugars to a heavy based pan over a medium heat. Allow to melt together swirling the pan every now and again to help them. When it starts to bubble, give it a couple more minutes. Then turn off the heat and pour in the cream, be careful as you do as this can squirt a bit. When it has cooled enough so that you won’t burn your mouth, start adding the salt a little at a time until to your taste. (I make it slightly less salty than i want, as i add more salt on top of the cake)