Place the cranberries in a bowl, add the brandy and set aside for at least 4 hours, stirring occasionally.
In a blender puree the chestnuts with the marzipan until they form a smooth, sticky mixture. Add the cacao (or cocoa), ground almonds and cranberries (along with the syrup from soaking if it hasn't all been absorbed) and stir thoroughly to combine. Cover and refrigerate for at least 30 minutes.
Spread some cocoa/cacao powder (or icing sugar, crushed nuts, or whatever other ingredient you'd like to use for coating) over a large plate. To form the truffles take a small amount of the mixture and using 2 teaspoons start scooping back and forth between them until the mixture starts forming round shapes (they don't have to be perfect). Roll the truffles in the coating mixture with the back of your hand and place in a bowl, cover and refrigerate for up to 2 days.
Making the truffles: When it comes to forming the actual truffles I recommend using 2 teaspoons rather than your hands (less messy). Just scoop a small amount of the mixture back and forth between the spoons a few times until it forms a more or less round shape. Then roll it in your coating mixture (cacao/cocoa, icing sugar, crushed nuts, desiccated coconut etc) until your balls are as round and as neat looking as you want them to be. You can make small or large truffles (using the proportions in the recipe you should get between 18-20 large ones).
Cocoa: You can use either cacao or cocoa powder in this recipe - I tend to use cacao in all my chocolate recipes as it's a little more nutritious than cocoa. (Check out also this collection of 27 everyday healthy cacao recipes).
Coating ingredients: Use cocoa/cacao, dark chocolate flakes (I used a grater to make mine), crushed almonds/nuts, desiccated coconut or even powdered sugar.
Storing: These dark chocolate truffles can be refrigerated, covered, for up to 2 days.
Not suitable for freezing.
Preparation time includes the time needed to refrigerate the mixture before making the truffles.