Combine sugar and water in a medium saucepan over medium-high heat.
Swirl the pot gently but do not stir.
Cook the mixture until it turns a light amber color, about 13-14 minutes.
Watch carefully to ensure it doesn’t burn.
Remove the pan from heat and slowly whisk in heavy cream.
Be cautious, as the mixture will bubble vigorously.
Stir in butter until fully melted and combined.
Add vanilla extract and salt for flavor.
Allow the sauce to cool before transferring it to a jar for storage.
You can serve it warm or refrigerate for later use.