Grease and line a 20cm square baking tin.
Cut butter into small pieces and add cream into a microwaveable-proof bowl. Microwave on high until butter is melted. Set aside.
In a small saucepan, combine water and golden syrup over a medium heat.
Add in sugar, being careful to not get any on the sides of the saucepan as this will burn (if you do get some, brush off with a wet pastry brush).
Put a candy thermometer into the saucepan and bring the mixture up to 160°C. This needs to be PRECISE.
As soon as the sugar mixture reaches 160°C, add in roughly 1/4 of the butter and cream mixture and stir.
Keep repeating this process until all of the butter and cream mixture is incorporated. Be careful as the mixture can spit.
As the butter and cream has cooled our caramel, we are bringing it back up to 118°C. Stir in table salt before pouring into prepared baking tin.
Transfer the caramel to the fridge and allow to cool for 30 minutes before sprinkling over the sea salt.
Return to the fridge and let the caramel set for around 4 hours or overnight.
Once set, remove the caramel from its tin and slice into bite size pieces. If it starts getting too sticky, return to the fridge to refirm (or lightly greasing your knife helps too).
Wrap each caramel up in waxed paper and ENJOY!