Add drained pineapple and chopped nuts to prepared Jell-o, pour into a cake pan and refrigerate to set.
Combine the cream cheese and whipping cream and beat until well blended. Spread cream cheese mixture on top of set Jell-O.
Using the reserved pineapple juice, prepare pineapple sauce on the stovetop. Combine pineapple juice, sugar, flour, and beaten eggs in a heavy saucepan. Stir constantly over medium heat until thickened. Add a squirt of lemon juice to the thickened sauce. Allow sauce to cool a bit before spreading sauce on top of the cream cheese layer.