With electric mixer beat eggs yolks and sugar until lemon colored. Add cornstarch, salt, vanilla. Add milk a little at a time until blended. Cook over low heat, stirring constantly, until thick. Add 1/2 stick of butter and let cool. Toss peaches with powered sugar. Spread 1/2 of the custard in the bottom of each pie crust. Top with peaches and whip cream.
Note: I use the custard in one pie and 4 large peaches.