Combine sugar and cocoa. Mix thoroughly. Add milk, stirring until mixture is smooth. Heat until mixture comes to a boil. Continue slow boil, stirring only occasionally to remove mixture from sides of pan. Cook to soft-ball stage (238 degrees). Remove from heat. Allow to cool for 5 minutes. Stir in butter or margarine and vanilla. Beat hard until fudge becomes very thick and starts to loose its gloss. Pour out into a buttered plate. When cooled, cut into small squares.
Taken from: It Never Turns Out The Same Way Cookbook A Collection of Recipes from the Kitchen of Joyce and Clem Kohl