Adapted from Epicurious

7 oz good quality plain chocolate, broken into squares
¼ cup double (heavy) cream
1 ½ tablespoons Framboise (raspberry) liqueur
6 oz fresh raspberries (1 cup)
½ cup unsweetened cocoa powder, you may need less

Put the chocolate and cream into a glass bowl and heat very gently in the microwave for 1 minute - stirring every 20 seconds until chocolate is melted and mixed with the cream - it may take a couple of minutes depending on your microwave, or melt in a double boiler over simmering water.
Stir in Framboise.
Put raspberries, a few at a time, into chocolate mixture and gently turn to coat using a fork or a teaspoon, then scoop them out, one at a time and put them onto a tray lined with baking parchment paper.
Chill for at least an hour.
Put the cocoa powder into a plastic bag and add the truffles, shaking gently in the bag to coat them. Transfer onto a plate and keep chilled until ready to serve.
These can be kept for up to 2 days in the fridge.