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; the 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.