1 package (4 serving size) Jello, in the flavor of your choice. I used orange this time. Cherry is also good. Sugar-free is probably fine.
1 cup boiling water
1 cup coconut milk (dairy milk, cream, soy milk, or whatever you prefer would probably work)
2 tablespoons cocoa powder
Mix Jello with boiling water as directed.
Mix cocoa powder into coconut milk until smooth. Pour coconut milk into liquid Jello in place of additional water. Stir well. Refrigerate four hours or so.
This has a tendency to separate into layers. If this is not desired, stir after 2-3 hours - when it has some form, but isn't quite set.
It's also tasty this way without the cocoa powder.
If you use a different size of Jello, just adjust amounts appropriately - the milk replaces the cold water.
I admit, I really did just prepared this. That part is not April Fools.
Posting it here, on the other hand...
Should you want to make this in a vaguely more paleo-friendly manner, or at least a healthier manner, use plain gelatin (you could even make it yourself with your leftover bones, but I'm not clear on how to do that and have it not taste like meat) or agar mixed with fruit juice for the gel part.