As a teenager, my mom (Billie Blair aka Witch1-2-3) used to make this fudge on the family farm at Summit Ridge, CO for her younger cousin Judy. Years later, even as a grown woman with children of her own, Judy would come visit and ask mom to make this fudge. Judy is coming to see me next week and I want to surprise her with mom's fudge.
I think the clue to this perfect fudge is: #1 make it in a cast iron skillet, #2 don't leave it alone and test for that perfect soft ball stage, and #3 allow to cool down 5 to 10 minutes without touching it.
In a cast iron skillet combine sugar, cocoa and salt. Mix with a spoon.
Add milk, begin mixing and turn on heat to medium low
Constantly stir as it boils. It will foam up slightly then begin to decrease. This is when you want to start testing for a soft ball stage.
Testing for doneness: Allow some of the syrup to dribble off the spoon into the bowl of cold water. When you can push the fudge together using your fingers in the cold water remove the skillet from heat and do not stir. Allow the skillet to sit on the back of the stove heat off.
Do NOT STIR! Add 1 TBSP of butter diced up and 1 tsp of vanilla. DO NOT STIR for about 5 minutes. If adding nuts, add them and begin to beat the fudge with a spoon. Pour into a lightly buttered dish and allow to firm up before cutting.