You got me thinking, too...
I don't like to use the artificial sweeteners much. That being said, I do have some sugar-free syrups that I love (vanilla and caramel) so maybe that could be worked into a recipe.
Here are a couple of recipes I found that don't use any artificial sweeteners. This one
relies on bananas. I don't normally eat bananas, maybe once every month or two, but for a delicious sweet treat it might be worth it! I'd definitely add cinnamon to the recipe.
has two recipes - the first one uses whole wheat flour and unsweetened applesauce, the second one uses bananas and dates... whoa, but I just noticed they both use 1/3 c. vegetable oil. That seems weird. I'd probably change that. But I'm always messing with recipes anyway so these seem like a good place to start.
A bit OT, but some of the Lara Bars have literally three ingredients - the ones I've seen always use dates. The Peanut Butter Cookie ones are made of peanuts and dates and salt. The Cherry Pie flavor is made of dates and almonds and cherries - and it's surprisingly sour - I loved it! Maybe there's something to this idea of making cookies with dates (yes, I know they are *sweet, sweet* but at least it's not processed sugar and these would be for an occasional treat).
ETA: oh, but I didn't really answer the question about brown sugar... I think the molasses idea sounds great if people are OK with having a little "real" sugar in there - not a problem for me as I'd only make these for special occasions. And if they were good , I'd probably have to give them all away