Banana Pineapple Fluff

1 cup milk
1 pound marshmallows
4 bananas, sliced
2 tsp. lemon juice
2 cups crushed pineapple, undrained
1 pint whipping cream
16 graham crackers, finely crushed
1/2 cup chopped walnuts

Heat milk; add marshmallows and fold over and over until dissolved. Cool. Sprinkle bananas with lemon juice. Fold into cooled mixture along with pineapple. Fold in whipped cream. Butter an 8 x 12 pan. Line with crackers and nuts. Pour in whipped mixture. Refrigerate until set.