There is a TV program on Channel 4 here in the UK called Cook Yourself Thin, presented by chef and food writer Gizzi Erskine. She shows alternative ways of cooking typical dishes to reduce the fat and calorie content. Most of this is just common sense if you're someone who already monitors your diet (such as substituting low fat yoghurt for sour cream), but she does have some clever ideas.
In particular, Gizzi often uses grated or mashed vegetables in place of butter in baking. She has a turkish delight brownie recipe that uses mashed sweet potato. Her baking recipes do still contain quite a large amount of sugar, and she also often uses substantial amounts of chocolate, however she also uses low GI ingredients, such as ground almonds. The main purpose of these alternative recipes seems to be to provide all the richness of the original, but with far fewer calories, and which (due to the low GI ingredients) are satisfying from smaller portions.
I particularly like the look of her strawberries and cream cupcakes, which use grated courgette (zucchini), and a meringue icing, cooked gently over boiling water. I imagine that these wouln't keep very well (due to the lack of butter).
