Heat the sugar in a heavy saucepan, something like 2 to 3 quarts, on medium-high heat until melted, constantly stirring with a whisk or wooden spoon. If the sugar boils, stop stirring and swirl your pan.
As soon as all the sugar has melted (it should be a medium amber color) add the butter to the pan and whisk until melted. (The sauce may bubble)
As soon as the butter has melted take the pan off the heat, wait 3-4 seconds, and slowly pour in the heavy cream while whisking. The sauce will foam up. That's why you need a bigger saucepan.
Whisk until smooth. Let cool in the pan for a couple of minutes then pour into a mason jar. Store in the refrigerator for up to 2 weeks. Serve warm. You'll love it!