Yes, chocolate tamales are a thing. The easiest way to make them may be to mix some cocoa powder into the sweetened masa ...

These homemade tortillas start with a dough made from whole-grain ... The resulting dough, called masa, is the basis for corn tortillas, chips, tamales and other specialty corn foods.

“If you haven't tried making cooked-masa varieties of tamales ... They are ready when the wrapper peels off easily and the dough looks firm. Tamales go in the steamer vertically.

I know the word “masa” means dough ... an alkaline substance to soften its hull and make it more nutritious, then grinding it into a dough that can become a variety of traditional products.