Dissolve Jello in boiling water. Reserve 1/4 cup for icing. Add strawberries, pineapple and bananas. Chill until firm, then top with icing. Pour into a 9 x 13 Pyrex container. Chill until firm, then top with icing. For topping, soften cream cheese and beat in powdered sugar. Add vanilla and whipped cream. Add the 1/4 cup of Jello. Spread on top of Jello mixture. Sprinkle top lightly with the 1/2 cup chopped nuts. Make one day before serving.