In a 1-quart bowl, microwave margarine, chopped mushroom stems, and scallions on High (100% power) 30 seconds. Stir; continue to microwave on High 2 minutes or until vegetables are tender. Stir in bread crumbs and cheese. Mound 1/6 of the mixture into each mushroom cap and arrange on outer edge of round plate. Microwave on High 60 to 90 seconds or until caps are hot and filling is sizzling. Makes 2 servings, 3 mushrooms each. Each serving provides: 1/2 Pro Ex, 1/2 Brd Ex, 2 Veg Ex, 1 Fat Ex. Per serving: 152 cal, 7 g pro, 9 g fat, 12 g car, 378 mg sod.