Recipe(tried): Homemade Hot Fudge Sauce (re: hard chocolate icing)

I think this might be what you are looking for. My Gram used to make it and put it over ice cream. It made a hard shell over the ice cream and boy was it yummmmmy. Good luck

HOMEMADE HOT FUDGE SAUCE

3/4 cup sugar
1/2 cup Hershey's unsweetened cocoa powder
2/3 cup evaporated milk
1/3 cup light corn syrup
1/3 cup botter or margarine
1 tsp. vanilla

Combine sugar and cocoa in a medium saucepan; blend in evaporated milk and corn syrup. Cook over low heat; stirring constantly, until mixture boils. Boil and stir for one minute. Remove from heat; stir in butter and vanilla. Serve warm.

Note: This sauce can be refrigerated for later use. Reheat in saucepan over very low heat, stirring constantly.

Makes 2 cups sauce.