This recipe was loved at our dessert last night so I thought I would post it for future reference. From Better Homes and Gardens New Cook Book (I love this book, btw--a classic):
Hot Fudge Sauce
3/4 cup semisweet chocolate pieces
1/4 cup butter
2/3 cup sugar
2/3 cup evaporated milk
In saucepan, melt chocolate and butter. Add the sugar, gradually stir in milk. Bring to boiling; reduce heat. Boil gently over low heat for 8 minutes, stirring frequently. Serve warm over ice cream. Serves 8.
Note: We had a little "detour" in our plans last night and I ended up not boiling for quite as long and "held" it on the warmer eye on low for close to an hour, stirring occasionally. The recipe held up great so I would think it would do just as well being "held" in a crockpot for a party or such.