In a heavy saucepan, melt butter over medium heat. Add the sugar, lemon juice, lemon peel and salt. In a bowl, beat eggs and yolks; add to butter mixture. Cook and stir until filling reaches at least 160° and coats the back of a metal spoon.
Remove from the heat. Cool quickly by placing pan in a bowl of ice water; stir for 2 minutes. Press plastic wrap onto surface of filling. Refrigerate for several hours or overnight.
Spoon half of the ice cream into pastry shell; freeze. Spread with half of the lemon filling; freeze. Repeat layers. In a small bowl, beat cream on high until stiff peaks form. Pipe or spread over pie. Cover and freeze for several hours or overnight. Yield: 6-8 servings.