Heat the sugar in a pot set over medium low heat.
When it starts to melt around the edges, use a spatula to pull it away from the sides of the pot and toward the center.
Once fully melted and amber in color, whisk in the butter. If the caramel separates, take it off the heat and keep whisking until it comes back together, then return it to low heat.
Slowly pour in the cream and whisk. Bring to a low boil, then turn off the heat, and add salt. Store in the fridge until ready to eat (serve warmed up).