Another approach to consider (this is what I'd try, for myself) is to leave the cream quantity alone, add another egg, add a half cup of reduced* pumpkin puree, a tsp of molasses and lots of "pumpkin pie spice"...you get the colour from the pumpkin, and some of the fiber, and the flavour is mostly in the spicing IMHO.

* I'd 'saute' pumpkin in a nonstick pan stirring constantly on low heat til some of the water is steamed off and it's thickened.

Next batch (may be a while, got in-laws visiting!) I'd certainly like to give that a try. Pumpkin sounds like a great idea!