I got this recipe from my mom's microwave cookbook that came with their first microwave (back in the '80s). This sauce is great on ice cream (and pretty much anything you put regular hot fudge on). For best results, serve warm.
To heat, microwave for 30 seconds at a time on medium to low power. I've put the sauce in a canning jar to give as gifts.
I'm working on adding some recipies from various cookbooks, and this one came from the Pampered Chef Stoneware Sensations. I haven't tried it yet. I'm guessing that it doesn't have to be cooked on a cooking stone.