I know posting two food product reviews in one day is a little odd (see VitaTops entry from earlier today if my statement's confused you).
But go with me on this one. They're somewhat related, in terms of being reasonably good for you sweet treats.
The best-tasting and filling cookie I know of is The Original Breakfast Cookie made by Erin Baker's Wholesome Baked Goods.
When I first heard of these, some girlfriends from the construction magazine I worked for said they were great, and did I want to split a big order with them? I thought it soundly mildly crazy to pay about a dollar each for breakfast cookies, but my office mate, Becca, said they were "crazy good." She was right. (I defer to her good taste in nearly all food matters. Except perhaps sushi. I'm a California Roll kind of girl.)
We got a mixed batch, and I soon found my three favorites: Mocha Cappuccino, Pumpkin Spice (which is only available October through December), and Vegan Peanut Butter Chocolate Chunk. I really recommend the Baker's Sampler so you can find your favorites. They also freeze well. The last time I checked, if you live in Michigan, you can only order Breakfast Cookies online. If that is no longer the case, please let me know where to buy them!
I suggest half a cookie as one serving because they're very filling. Also, after you read the package information, you'll see that half a cookie is much more in line with one serving. That said, an whole cookie is a quick meal substitute for breakfast or lunch.