Over medium heat, put the sugar in a sauce pan. It will form clumps and eventually melt and brown. It’s preferable you don’t stir, just shake the pan a bit but if you must use a rubber spatula or wooden spoon
Once it has browned add in the butter and be careful as it might splatter. Mix it in
Slowly drizzle the cream and allow it to boil for a minute
Remove from heat and add the salt
The sauce will thicken as it cools down, store in fridge up to a month