- Combine corn starch, salt, sugar, corn syrup, chocolate and milk in a heavy saucepan and cook over low heat until well blended.
- Cook to 238 degree F, stirring frequently.
- Remove from heat and add butter. ( DO NOT STIR ).
- Cool to room temperature.
- Add vanilla extract, beat until firm.
- Pour onto buttered platter.
- Serve immediately or chilled