Combine sugar, flour, and salt in a medium saucepan; add milk, stirring until smooth. Cook over medium heat, stirring constantly, until thickened and bubbly.
Gradually stir one-fourth of hot mixture into eggs; add to remaining hot mixture, stirring constantly. Cook, stirring constantly, 2 minutes or until mixture thickens. Remove from heat, and gently stir in butter and vanilla. Pour into chocolate wafer piecrust. Chill completely.
Garnish with fresh raspberries and whipped cream.
Note: Fresh blueberries, kiwi, pineapple, or strawberries may be substituted for raspberries.