Blend the dates, peanut butter, salt and vanilla extract in a food processor until a smooth, sticky paste forms.
Melt the dark chocolate in a heatproof bowl over a pan of gently simmering water, or in short bursts in the microwave.
Spoon a layer of melted chocolate into the base of each muffin mould and spread it slightly up the sides.
Add a spoonful of the peanut and date mixture to each mould and gently press it down.
Spoon over a layer of the peanut butter caramel.
Cover with the remaining melted chocolate, ensuring the filling is fully enclosed.
Sprinkle with the chopped roasted peanuts.
Place in the freezer for 20–30 minutes, or until completely set.
Remove from the moulds, sprinkle with flaky sea salt and serve.