Mystery Ingredient: Cake edition

I love sweets.  A lot.  Especially chocolate.  But obviously sweets tend to have a great deal of calories and very little nutrients.  I like the challenge of modifying dessert recipes to be lower sugar and lower fat, without resorting to artificial sweeteners and fake-y ingredients.  I found this one on Eating Well's website.  Here's a picture of the finished product (okay, admittedly I could've done without the mini chips on top, but they're just so cute!):

So what's the mystery ingredient?  Here are a few hints: adding it allows for way decreased oil, it provides some fiber and a big dose of Vitamin A...

Pumpkin!  I know what you're thinking- "gross!"- but the flavor of the cocoa overtakes any pumpkin taste, and allows for a moist, dense cake.  Bonus points to this recipe for using some whole wheat flour.  Here's a link to the recipe.  So far it gotten the approval of my husband and my coworkers:
Chocolate Pumpkin Bundt Cake
P.S. You can swap out the 1 egg + 1 egg white for 3 egg whites (lower fat!  lower cholesterol!) and cut back the sugars by 25% and it'll still turn out the same.