Pour the sugar and water into a saucepan and heat. Let boil at medium heat until the sugar is fully dissolved.
Take the saucepan off the stove and add the heavy cream. Stir well before putting the saucepan back on the stove.
Add the butter in small pieces then let the liquid simmer until it thickens. The caramel is ready when a drop, poured on a cold glass, sticks to it but stays soft after having cooled down.
Pour the caramel into silicone candy molds and let cool fully before unmolding, or pour the caramel on parchment paper and cut into squares before it fully sets.
The caramels can be saved two weeks in a sealed container, ideally wrapped in wax paper or parchment paper.
These sweets from Brittany are addictive - and a bit sticky, be careful if you have fillings.