Pirozhki as solution to picky eaters

As any toddlers, my kids are fairly picky. My youngest A. (2) is just entering that stage, while my oldest L. (3.5) is slowly exiting it (I hope). One thing I've been trying is making pirozhki. With bread machine, making the dough is quite easy. The trick is finding interesting and healthy stuffing. So far, I've tried apple & banana (bleh: mostly banana's fault, I think) and eggs&rice (yum-my!). The kids are instantly attracted to them, they're easy to pack, and most freeze well. Next up: try a more whole wheat dough (as it is, we hardly ever eat white bread) and try more kinds (chicken & celery; frozen cherry; etc).