Stir German chocolate, 1 stick butter, salt, sugar, and evaporated milk in saucepan. Bring to a full boil, reduce heat, boil 4 minutes. (MUST cook at least 4 minutes.) Remove from heat, add vanilla, cool.
Crush cookies and combine with 1/3 cup butter. Pat into bottom of a 9x13 inch pan. Slice 1/2 gallon ice cream and pat on top of cookie layer. Cover with chocolate fudge sauce. Place in freezer 1/2 hour. Top with Cool Whip and slivered Hershey bar. Keep frozen. Remove 15 minutes before serving.