"This makes a rich but surprisingly light, torte. An absolute, worth-the-price-of-the-book winner. Mashed sweet potatoes make a great substitute for the traditional pureed chestnut paste. Chestnut puree is available kosher, but I have never been able to find it "kosher for Passover." It may seem unusual, but I can assure you of two things ? it tastes divine and it is easier than buying fresh-in-the-shell chestnuts, roasting, poaching, and grating them to get them ready for this cake. You can also serve this in squares, as French-style "petit fours." The glaze slicks this up but is not necessary?a dusting of cocoa is just fine...."