Melt some cocoa butter, mix in sugar and black cocoa. Done!
The result should be grey or black.
This isn't a recipe, just an outline of one... I'm deliberately not specifying the proportions of the ingredients, nor even say whether you should dip things in the stuff, or mold and cool it, or maybe temper it, etc.
Whether you add other flavors, such as vanilla extract, or milk solids, or chocolate extract, or natural cocoa, or dutched cocoa, etc, is up to you.
If you haven't got any cocoa butter, you might substitute chocolate. Almond bark also might work, though I wouldn't call the result chocolate.
Remember, Halloween is a mere 10 weeks away, so it's not too soon to start planning some creepy confections.-- goldbb, Aug 23 2016 Gray-ish chocolate is common http://acselementso...ERINGCHOCOLATE.htmlIt is the result of not "tempering" the cooling chocolate correctly. [Vernon, Aug 23 2016] Isn't this the recipe for making...chocolate?-- zen_tom, Aug 23 2016 No, it seems to be recipe for making chocolate- flavoured grey.-- MaxwellBuchanan, Aug 23 2016 Here's a recipe for making purple chocolate: melt some cocoa butter, add sugar and purple emulsion. Done! Other colours are available. In fact any colour of chocolate is available using this simple method.-- xenzag, Aug 23 2016 [Ian] If you're making chocolate for extraterrestrials, it should match their skin tone -- grey for Gray aliens, etc.
[xenzag], black cocoa is a type of dutched cocoa, which just happens to be black. So, the result will taste like ... perfectly ordinary chocolate. If more than one fifth of your resulting candy is black cocoa, it could be legally classified as "chocolate" in any country which regulates the term.
I can't imagine that whatever purple coloring you are thinking of, might like taste like chocolate or be legally classified as such.
[Vernon], Chocolate bloom is not my goal here. Obviously it could happen with gray chocolate, but that's not the point of this idea.-- goldbb, Aug 25 2016 Why do you belive that mixing cocabutter cocoa and sugar would be grey? In every case I've seen the result is brown.-- WcW, Aug 25 2016 random, halfbakery