Melt the butter in a large pot over medium-high heat. Add the cream and whisk gently. When warm, add the brown sugar and salt, and whisk until smooth. Bring to a boil, then reduce heat and simmer for a few minutes.
Remove from the heat and carefully add the vanilla (the mixture will bubble quite a bit!). Stir and then pour into a container. Use as a sauce for ice cream.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.