In a small saucepan, combine the sugar and melt it over very low heat. This step can take a long time, so be patient.
Meanwhile, heat the single cream. Once the sugar has completely dissolved and turned a caramel color, remove the pan from the heat and add the hot single cream.
Be careful not to splash.
Mix everything well, then return to the heat for a few minutes. Turn off the heat.
Add the softened butter, stirring constantly.
Add the single cream.
Pour the mixture into a glass jar and let cool to room temperature.
Store the caramel in the refrigerator.
