01 - Place sugar in a medium saucepan over medium heat. Stir constantly until sugar melts and turns a golden amber. Add the butter and continue stirring until combined and melted. Slowly pour in the double cream (mixture will bubble). Stir until smooth. Remove from heat and stir in salt and vanilla extract. Let cool completely.
02 - In a large bowl, whip the chilled whipping cream to stiff peaks using an electric mixer. Gently fold in the sweetened condensed milk until combined.
03 - Fold 1/2 cup of cooled salted caramel into the whipped mixture, creating visible streaks of caramel if desired. Transfer mixture into a loaf pan or airtight freezer-safe container. Drizzle more salted caramel over the top and swirl lightly with a knife.
04 - Cover with plastic wrap or lid. Freeze for at least 6 hours, or until firm.
05 - Let sit at room temperature for 5 minutes before scooping. Enjoy plain or with extra salted caramel.