Preheat oven to 450º. Bake pie shell for 8 min, or until golden brown. Cool on rack.
In a small saucepan, mix sugar, salt and cornstarch. Stir in milk. Cook, stirring, over medium heat until mixture thickens and begins to boil. Boil for 1 min.
In a small bowl beat egg yolk, add about 3 tablespoons of creamed mixture, pour back into saucepan with creamed mixture. Cook, stirring constantly, until mixture is thick and bubbly. Stir in vanilla and almond extract. Remove from heat. Pour into a medium bowl, place waxed paper over surface of custard and refrigerate for 1 hour.
Roll almond paste into a 6” circle between 2 sheets of waxed paper. Remove top piece of paper and invert circle of paste onto bottom of pie shell; remove wax paper. Spread custard over almond paste. Spread apples over custard.
In a medium bowl, beat heavy cream with confectioners sugar until stiff. Spread over apples. Refrigerate 2 hours before serving.