In a saucepan, mix sugar, flour, and salt. Add 1 cup of milk, mix until smooth. Bring to a boil over medium heat, stirring briskly. Continue to stir and boil until smoothly thickened. Remove from heat. Beat eggs with remaining cup of milk. Gradually stir into hot mixture. Then put back over heat. Bring to a boil, stir until mixture thickens more. Remove from heat. Stir in butter, chocolate chips, and vanilla. Blend until chocolate is melted. Pour into pie shell and chill.
Recipe by Amish 365 at https://www.amish365.com/amish-chocolate-dream-pie/