Whole Wheat cookies? (Melon Bread)

My fiancee and I are anime fans and a while back I felt adventurous and tried making Melon bread, based on a recipe I believe I found on this site.  (for those who don't know, Melon Bread is basically a bun type thing, that has a sweet bread, with a sugar cookie sort of crust laid over it.)

it came out pretty well,  definitely able to see the reason its popular in japan.

but health-wise, they aren't so hot.  by weight watchers points, they werel like, 4-6 points each or something like that.

so I thought of trying to make a version thats healthier.   now for the bread-portion, I am fine, I have been experimenting with substituting WW flour for regular and such.

but for the cookie portion...  it seems a bit trickier.  (I mean, how often do people make COOKIES with whole wheat flour?)

I tried doing two main things with my first attempt at making healthy melon bread, I substituted part of the sugar, with Splenda, and used 100% whole wheat flour.   while it did not end up BADLY, I was profoundly unimpressed with the cookie crust.   while it did seem to prevent the bread from crusting up early(quite well, in fact, the bread portion was wonderfully soft and fluffy) and never got remotely crispy, in fact it was hardly distinguishable from the bread portion.

the regular flour cookie portion of the recipe I am using is:

1c Flour (with the straight recipe, I mixed AP and cake flour, though I'm not sure the distinction mattered that much)
1/2 tsp baking powder
3Tbsp Butter
4Tbsp Sugar
1 egg

(sugar/buter creamed, mixed with egg,  then the baking powder/flour mixture mixed in.  portioned and refrigrated, then rolled out and put on top of the mostly proofed buns)

is it possible to do something like this with whole wheat flour and it work better than I experienced? larger volume overall? more baking powder?  would using only half WW flour improve it greatly or would the WW flour weigh it down too much even then?

I'm not averse to experimenting if thats what it takes, but if I can get a direction thats more likely to work, that would be appriciated.

also, how does Splenda interact with bread baking or cookies like this?