How to Make It
Melt the butter in a large saucepan over medium-high heat. Add the sugar and cook, stirring frequently, until smooth, 2 to 3 minutes.
Add the heavy cream. Simmer, stirring occasionally, until thickened, 10 to 12 minutes. Stir in the vanilla extract and ½ teaspoon salt; let cool. Refrigerate for up to 1 month.