I got the idea for this from The Garlic Farm where they've got a recipe for black garlic brownies and I thought if you could do it with dark chocolate brownies why not truffles too. Although if you don't like garlic (a lot) I wouldn't recommend this, I would say it was a bit like adding chilli to dark chocolate (a bit, not quite) oh and the only place I know of to get black garlic butter is the garlic farm web page.
Always sieve your cocoa and icing sugar first to make things as easy as possible to mix in. You could also add some mint extract or put a hazelnut in the centre or you could crush some hazelnut or pistachios and add them to the mix or make a white chocolate truffle with added strawberry and use that in the middle or dust with cocoa instead of icing sugar or even do a milk chocolate with malt extract to. You could make a whole range of truffles with garlic if you wanted :-)