I usually take a normal recipe and just start making healthy changes. I would probably use a recipe like this one: www.afarmgirlsdabbles.com/2011/03/17/snick
Here are my healthy changes:
Use white whole wheat flour instead of all purpose. Mix the flour in a blender or food processor so it has the finer texture of pastry flour.
Replace the butter with fat free plain yogurt (works very well in cake and brownie recipes)
2 large eggs and 1/3 cup egg whites instead of 4 eggs
Use fat free evaporated milk instead of regular milk
Iceing - Mix 1/4 cup fat free cream cheese with 3 tablespoons light butter until light and fluffy. Add 1/2 cup powdered sugar and mix that in. Repeat until you added in about 3 cups of powdered sugar (1/2 cup at a time.) Add 1 teaspoon vanilla extract and 1/2 tablespoon fat free milk and beat that in too until well combined. Ok, this still has too much sugar in it, but it tastes great and much less fat then most frosting recipes.