My god. I’m a bit immodest about it, but it really is that good. Here’s what I did:
[ul]
[li]Sloooooowly melt, then carefully caramelize one cup of plain, dry sugar over medium-high heat.[/li][li]Wait until the color of the whole mess is a deep, rich amber.[/li][li]When the first, tiny wisp of smoke is evident, remove the pan immediately from the heat. Tempt fate on this one, and you’re likely to end up with a pan full of charcoal. [/li][li]Lower heat to medium or medium low.[/li][li]Slowly trickle one cup of heavy cream into the caramelized sugar. Stir constantly.[/li][li]Some sugar will harden on contact with the liquid. No worries.[/li][li]Place mixture back on lowered heat. Add 1 teaspoon (real) vanilla extract, and one tablespoon of plain cocoa. Use the good stuff, cheapskate. :)[/li][li]Stir constantly until the mixture heats back up and the sugar dissolves completely. During this time, the chocolate will dissolve (become suspended? enter a colloidal state?), and the mixture will turn rich, dark brown.[/li][li]While still hot, strain through a fine sieve to remove any large cocoa chunks that may be left.[/li][/ul]
I served it over vanilla bean ice cream while still warm, and my normally rather reserved girlfriend licked her bowl clean.
Aw yeah. 
Oh, and what kind of cocoa did you use? I’m a Valrhona gal, personally. Hershey’s is pale and chalky in comparison.