Toss in a can of chestnut puree and enjoy the truffle-like texture and taste of these brownies. Topped with a thick coasting of chilled ganache frosting, these are simply divine. They are rich but unexpectantly light and more like a French chocolate pastry/cake. Cut them semi-frozen, using a cookie cutter or sharp knife to make small diamond shapes which you then serve in paper pastry cups as a confection. These freeze very well.