We love stuffed portabello mushrooms. My usual filling is a combination of the stems, long grain and wild rice, with sausage, onion, celery, bread crumbs and parmesan cheese. Every thing is chopped finely, mixed and mounded into the cap. This works with the large size, and the bigger "baby" ones. I also drizzle the mushrooms with melted butter before filling, then bake. In our family it seems like I never make enough!