Zest the limes as needed for the recipe
Slice each lime in half and juice them
Use a spoon to scoop out any remaining flesh from the lime halves
Add heavy whipping cream, sugar, salt, vanilla, and lime zest to a small saucepan over medium heat
Bring to a simmer, stirring often, then reduce to low and gently simmer for 5-6 minutes
Strain the hot cream through a sieve to remove the zest
Whisk in the lime juice right away until the mixture thickens slightly
Pour the mixture into the lime halves or small ramekins
Transfer to the fridge for about 4 hours to set
Optional: whip ½ cup heavy whipping cream with 1 tbsp powdered sugar until peaks form
Top each posset with whipped cream, crushed graham crackers, and a sprinkle of lime zest
Serve and enjoy
