Add 1/4 cup water (optional) and 1 cup granulated sugar to a heavy-bottom saucepan
Heat over medium-high, stirring only until sugar dissolves (then stop stirring)
Continue cooking until the mixture turns deep amber
Remove from heat
Slowly whisk in 1/2 cup heavy cream (careful—bubbles will form)
Whisk until smooth
Stir in 1 tbsp butter and 1/2 tsp vanilla extract (optional)
Add a pinch of salt (optional)
Let cool 5–10 minutes to thicken
Use warm or cool; store in an airtight container in the refrigerator up to 2 weeks
Rewarm gently to thin, if needed