Roughly crush the Cardamom in a pestle and mortar. Place in a saucepan with the cream and bring to the boil. Remove from the heat and leave to infuse for 30 minutes.
Tip the chocolate chips in a large bowl, place a sieve over the bowl. Bring the cream back up to boiling point, immediately tip through the sieve onto the chocolate. Press as much cream as possible out of the cardamoms and stir into the chocolate. If the chocolate does not fully melt, place the bowl over a pan of boiling water, stirring continuously until it has. Leave to cool at room temperature.
Once cold, beat with an electric mixer for 10 minutes, until thick and fluffy. Leave to set. This will take around 90 minutes at room temperature. Do not refrigerate, as this mixture will set too hard Prepare a truffle tray by taping parchment paper to a large baking sheet.
Liberally dust hands with cocoa powder, roll a teaspoon of mixture between them to form a ball and place on the tray. Repeat with the remaining mixture, place the tray of truffles in a refrigerator and chill until very firm. This will take about an hour. To coat, melt both chocolates in a bowl over a pan of boiling water, leaving to cool afterwards.
One tepid, stab a truffle with a cocktail stick and dip in the chocolate. Use another cocktail stick to ease it onto a clean tray. Repeat with both chocolates until all the truffles are coated. Leave to set at room temperature and serve with a dusting of cocoa powder.
