This recipe is from the wonderful cookbook, "A Treasury of Jewish Holiday Baking", by Marcy Goldman. This pareve Pesach cake tastes like a rich but light chocolate cheesecake. It's wonderful with or without the glaze. If you don't mind a dairy cake, it's also excellent with a regular ganache (with cream, etc...). Kids will LOVE this and won't even know they're eating a vegetable (you cannot taste the sweet potatoes). Enjoy! 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.