Cream the cream cheese and butter until smooth and creamy.
Add the lemon zest, lemon juice and salt, mix until combined.
Slowly add the powdered sugar and mix until light and fluffy.
If frosting is not to spreading consistency mix in more powdered sugar to the consistency you want.
Spread on prepared cake and store finished cake in the refrigerator.
Chef's notes: Separate eggs before you bring them to room temperature. They are easier to separate cold. The original recipe called for 6 inch cake pans and has been converted to 9 inch cake pans with adjusted baking time. You will need to keep an eye on it and check it at 15 minutes, then every 5 minutes until done. Don't overbake.