Chop the dark chocolate and put it in a small thick bottomed saucepan over low heat. Pour the cream little by little whisking to melt chocolate. Remove from the heat and mix in the butter and the tahini. Pour in a bowl and let rest in the fridge for at least two hours.

After two hours, it's time for kids to go on stage! Remove the truffle mixture from the fridge and dust generously a large dish with cocoa powder. Kids, roll up your sleeves, wear an apron and be ready to dirt your hands! With a teaspoon make small balls of chocolate mixture, large more or less as a hazelnut. Dust your hands with cocoa powder and roll the truffles in your hands, put them on the dish and roll them again into the cocoa powder.

Let them set in the fridge for two hours, then... the truffles are ready to be eaten or gift-wrapped for your best friends!