Drain pineapple, reserving juice; set the pineapple aside. In a saucepan, combine gelatin, water and reserved juice. Cook and stir over low heat until gelatin is dissolved. Refrigerate until syrupy, about 30 minutes.
In a small bowl, beat cream cheese until fluffy. Stir in gelatin mixture, walnuts, marshmallows and reserved pineapple. Fold in the whipped cream.
Transfer to a 1-qt. serving bowl. Cover and refrigerate for 2 hours or until set. Yield: 9 servings.