Boil cream with lime zest, sugar, and kaffir lime leaves.
Add citrus juices, return to boil, and stir in coconut.
Strain liquid through a fine sieve and pour into glasses.
Chill the posset in the fridge for 2 to 3 hours.
Rub flour and butter together until the mixture looks like breadcrumbs.
Mix in sugar, spices, zest, salt, and egg yolk to form dough.
Wrap dough in cling film and chill for 1 hour.
Preheat the oven to 180°C.
Roll dough on a floured surface to 5mm thickness.
Cut into 6cm rounds and place on lined baking trays.
Bake for 10 to 12 minutes until lightly golden-brown.
Cool on a wire rack and dust with sugar.
Mix mango salsa ingredients and refrigerate until needed.
Serve posset topped with mango salsa and biscuits on the side.