Hot Fudge Sauce

4 Tbsp. Butter
4 Squares unsweetened chocolate
2/3 c. Boiling water
2 tsp. Vanilla
2 c. Sugar
1/4 c. Light corn syrup
1/4 tsp. Salt

Melt butter in heavy sauce pan. Add chocolate and let melt. Stir in water, sugar, syrup and salt. Bring to a boil. Cook without stirring until thickened. It should look dark and glossy, about eight minutes. Add vanilla.