Place a pot on a low/medium heat and fill it half way with water. Place a heatproof bowl on top, making sure that the bowl doesn't touch the water (remove some water if necessary). Place 150g of the chocolate in the bowl, stirring occasionally until melted. Remove from the heat.
Spoon equal amounts of the chocolate into the pumpkin moulds (around 1 tbsp per mould). Draw the chocolate up the sides of the moulds with the back of the spoon. Place the moulds in the freezer for 15 minutes.
Meanwhile mix the peanut butter, icing sugar and salt together until smooth. After 15 minutes remove the moulds from the freezer and spoon 1 tsp of peanut butter into each pumpkin. Smooth the peanut butter mixture out as smooth as possible then place back in the freezer for another 15 minutes.
Meanwhile melt the other 150g of chocolate the same way as before. After 15 minutes spoon equal amounts into each mould, tap the moulds on the counter top so they are level then place back in the freezer for another 15 minutes until set. Enjoy straight away or at room temperature.