Line a baking tray (sheet) with silicone (baking) paper. Put the raspberry purée and invert sugar in a saucepan and bring to the boil. Take off the heat and leave to cool until it reaches 65-70°C (149-158°F).
Melt the chocolate over a bain-marie (water bath) to about 45°C (113°F) and gradually add the cooled raspberry mixture to the chocolate. Continue to mix t