Beat cream cheese until smooth. Gradually blend in the powdered sugar. Stir in lemon peel and lemon juice until smooth. Reserve 1/2 cup of this mixture and refrigerate for later use.
Beat remaining 2 eggs. Add vanilla. Beat this mixture into the cream cheese mixture until well blended. Spread over the cake mixture. Bake at 350° until set, approximately 25-30 minutes.
Spread the reserved cream cheese mixture onto the bars. Refrigerate until firm, cut into squares and serve.