2. Dice stems. Combine with butter and onion in 1 quart glass casserole. Microwave, uncovered, at level 10, 3-4 minutes, stirring twice. Add bread crumbs and parsley. Set aside.

3. Cover mushroom caps and microwave at level 10 for 2-3 minutes. Stuff each cap with bread crumb mixture. Cover and microwave at power level 10 for 2-3 minutes.