I first had this in a coffeehouse in Highwood Illinois in the 60's where my dad, my brother and I used to play folk music on stage. I was 6 or 7 at the time. I used to make this recipe at the Pump Room when I was pastry chef there in a 5 gallon bucket. We served "the World's Smallest Hot Fudge Sundae" (another one of Rich Melman's brilliant ideas) there which used only 2 tablespoons of sauce and still I had to make it every other day!
Put everything except the vanilla in a pot and bring it to a boil. Continue cooking until it looks like it's broken and separating. Take it off the heat, whisk in the vanilla; then blend it with a hand blender to smooth it out. Chill until ready to serve; then heat it up. Pour over scoops of ice cream, topped with whipped cream and chopped peanuts.