1. Place sugar in a medium heavy-bottomed saucepan and stir in 1/2 cup water.
2. Place over medium-high heat and cook, without stirring, for 15 to 16 minutes, until dark amber in color. Remove from heat and stir in salt. Gradually stir in cream and add vanilla.
3. Cool and spoon into jars. Tightly seal and store in refrigerator for up to 2 weeks.