bell peppers, with cheese.
We took the mushroom stems and pepper tops, chopped em up, and sauteed them withworcestershire sauce, balsamic vinegar, salt and pepper, and put that on top, filled in with white wine, and sprinkled with the final layer of cheese. Baked for about 45 minutes at 325 or so.
I'm sorry I don't have pictures, but it was described by the party as "awesome," and was really not that hard to make, since the olives come pre-stuffed and all. Really just assemble and stick in the oven.