Microwave sweet potatoes according to directions below. When cool enough to handle, peel and mash with potato masher or electric mixer. Stir in remaining ingredients except orange twist and parsley sprig. Spoon mixture into a 1-quart microwavable casserole. Refrigerate, covered, several hours or overnight.
Microwave (HIGH), covered, stirring once, until heated through (7-8 minutes). Stir. Let stand 3 minutes. Garnish with orange twist and parsley sprig.
To Microwave Sweet Potatoes or Yams
Rinse sweet potatoes, pierce skin with fork. Arrange in a circle of double thickness of paper towels in microwave oven. Microwave (HIGH), turning over and rearranging once, just until tender (12-14 minutes). Let stand 3 minutes.