1 Line a mini muffin tin with sweet cases.
2 Melt the chocolate with the coconut oil in a bowl over hot water. Spoon 1 tsp into each sweet case and leave to set. Put the remaining chocolate to one side.
3 Meanwhile, stir together the peanut butter with the butter and icing sugar, likewise in a bowl over hot water, until creamy. Cool until it reaches a piping consistency then spoon into a piping bag. Pipe onto the centre of each cooled chocolate, making sure not to touch the edge of the case so that the peanut butter is completely encased later.
4 Cover with the remaining chocolate (melt again if necessary). When it has just set, scatter with peanuts. Leave to cool completely and set firm.
5 Remove from the tin and serve.