In a medium saucepan, combine heavy cream, granulated sugar, kosher salt, and lemon zest. Heat over medium-low for about 3-5 minutes until steaming but not boiling.

Remove from heat and stir in freshly squeezed lemon juice. Mix gently until fully incorporated and sugar dissolves.

Carefully pour the mixture into prepared lemon halves, filling them to just below the rim. Place on a baking sheet.

Cover with plastic wrap or foil and refrigerate for a minimum of 4 hours.

Once chilled, sprinkle a thin layer of granulated sugar over each posset and caramelize with a blow torch until golden brown.

Serve immediately after caramelizing for the best texture.