As they say, I am a man of my worrrrd.
490g dark chocolate
225ml single cream
3tsp Grand Marnier
Melt 390g of dark chocolate, with the cream, in a double-boiler or in the microwave. Remove from the heat once melted and add the liquor. Leave it to cool, then cover with cling film and place in the fridge to set completely.
Line a baking tray with baking parchment. Remove the truffle mixture from the fridge and, by using a teaspoon, scrape a small amount of it, roll it into your hands to form some sort of ball and place on the baking tray. Continue until you have used all of the mixture. Return the truffles to the fridge to allow them to set again. This will take another hour or so.
Meanwhile, melt the remaining 100g of dark chocolate and leave to cool. Make sure you do not let it cool completely; if your house is cold enough, the chocolate will return to solid state and you do not want this to happen. Get the truffles out of the fridge and quickly dip them one by one in the melted chocolate. Roll them into the cocoa before placing them in little paper cups like the ones I used. Store all of these in an airtight container at the bottom of the fridge.