Olive's Fudge - From Mom

This chocolate fudge is quite good but the directions are a bit obtuse at the ending.  I kept the thermometer in and cooked the fudge until it read about 238.  When mom made this, she used regular cocoa.  I used Hershey's Special Dark to make a darker chocolate fudge.

  1/2 C Cocoa                                                                             1 Tsp Corn Syrup

  3 C Sugar                                                                                 3 Tbl Butter

  1/2 Tsp Salt                                                                              1 Tsp Vanilla

  1 C Evaporated Milk                                                               

Combine cocoa, sugar and salt.  Add milk, corn syrup and butter and cook on high until mixture boils, stirring occasionally.  Continue boiling without stirring until mixture is 232 degrees.  Add vanilla and continue to boil until vanilla loses its gloss.  Pour into a buttered pan and cool.