Meanwhile, make bottom layer. In 3-quart saucepan, combine granulated sugar, cornstarch and salt; mix with wire whisk. Blend in lemon juice and cold water, then add egg yolks and blend until smooth. Add butter and gradually stir in boiling water. Heat to boiling over medium heat, stirring constantly. Boil for 2 minutes. Remove from heat and add 1 teaspoon lemon extract, the lemon peel and yellow food color. Partially cool for 30 minutes and pour into the baked pie shell. Refrigerate for at least 30 minutes before adding middle layer.