Melt the chocolate in the top part of a double boiler. Add the condensed milk and stir over rapidly boiling water for about five minutes, until thickened.
Remove from the heat. Add the salt and enough hot water to soften the mixture to desired consistency. The sauce may be served warm or cold. It thickens upon cooling but may be thinned again with water.
Thin the fudge sauce with strong coffee in the place of the water.