In a medium-sized saucepan, combine sugar, cornstarch and gelatin. Add salt. Stir in milk. Stir constantly over medium heat. Cook for 7-10 minutes. Reduce heat.
In a large bowl, beat the egg yolks with vanilla extract. Whisk in a small quantity of the hot mixture of milk. Pour the mixture slowly back into pan while whisking continuously. Stir and cook over low heat for about 2 minutes, until the custard becomes very thick. Don't let it boil. Remove from heat.
Pour into the prepared graham cracker crust and chill for 2 hours. Pour into the graham cracker crust prepared and chill for two hours.
In a large bowl, combine heavy cream, vanilla extract, and sugar. Beat with an electric mixer at medium speed, until soft peaks are formed. Pipe on the chilled pie.
