this recipe from allrecipes.com:
- Grease an 8x8 inch square baking pan. Set aside.
- Combine sugar, cocoa and milk in a medium saucepan. Stir to blend, then bring to a boil, stirring constantly. Reduce heat and simmer. Do not stir again.
- Place candy thermometer in pan and cook until temperature reaches 238 degrees F(114 degrees C). If you are not using a thermometer, then cook until a drop of this mixture in a cup of cold water forms a soft ball. Feel the ball with your fingers to make sure it is the right consistency. It should flatten when pressed between your fingers.
- Remove from heat. Add butter or margarine and vanilla extract. Beat with a wooden spoon until the fudge loses its sheen. Do not under beat.
- Pour into prepared pan and let cool. Cut into about 60 squares.