Add the butter and sugar to a medium saucepan (I recommend grass-fed butter).

And the chocolate (broken into chunks). Use 1 ounce for "milk chocolate" and 2 ounces for "dark chocolate." It's a pretty deep chocolate flavor with 2 ounces.

Put it on low heat and let it all melt. This will take a little while. Don't turn it up higher to try to rush it. The sugar will burn before everything melts. Or the chocolate will burn. I learned my lesson making butterscotch sauce before. Just don't.

After it melts, allow it to cook for 5 - 10 minutes without stirring. It should be bubbling lightly.

Add the heavy cream now. Stir it in. This will thin the mixture some; that's okay. It's not done.

Allow it to bubble lightly on low heat for 10 minutes, again without stirring. It will thicken as it cooks.

Remove from heat and stir in the vanilla.