This started as a mistake, but it turned into quite a treat.
First, I started frying the peanuts in little bit of peanut oil in a small cast-iron skillet. Then I added it a bunch of sugar, mixing it the whole time. Then I added in the cocoa powder and kept cooking and stirring.
When I thought the sugar had caramelized enough, I stirred in some sherry and let it reduce a bit. Then I poured in the heavy cream, cooked it until it thickened a bit, and then poured it over vanilla ice cream.
I had a particular idea in mind, and it didn't go as planned, so I kept working on it and adding stuff to try to salvage it, and eventually it turned into an ice cream sauce. And a great ice cream sauce it made, too! There are crunchy chunks of crystallized sugar, and the chocolate sauce itself is fairly crystallized, as well. And the peanuts, freshly roasted in the pan and coated with sugar and chocolate, are delicious.
The leftover sauce, still full of peanuts, I put in the fridge, where I ended up nibbling at it by itself for the next week or so. Quite a treat!