I found this recipe on the back of a bag of Reese's PB Chips back in the 80's. I make it every year, at Thanksgiving & Christmas. It's really foolproof as long as you give the rolling boil time. It makes enough fudge for 2 parties or lots of gifts.
This recipe has been made by our family at Christmas for at least 15 years. My trick for (somewhat quickly) making a double batch: Prepare two 13x9x2 pans and prepare an entire batch of just peanut butter fudge (use the entire two cups of p.b. chips) and divide between the two pans, then do the same with the chocolate portion of the fudge. Homemade fudge takes a little time, effort, and patience, but this recipe is SO worth it. I like that this fudge recipe is timed rather than having to use a candy thermometer. Also, I have learned that cane sugar works best for all baking, but most especially when making candy. I've tried using beet sugar with this recipe but it came out gritty and didn't quite set up correctly.