1. Peel first 3 ingredients, and cut into 1 1/2-inch pieces. Combine parsnips, carrots, onions, and cranberries in a lightly greased 6-qt. slow cooker; layer sweet potatoes over top.
2. Whisk together sugar and next 4 ingredients in a small bowl; pour over vegetable mixture. (Do not stir.)
3. Cover and cook on HIGH 4 to 5 hours or until vegetables are tender. Toss with parsley just before serving.