Heat oil in a large skillet over medium heat. Add onion and garlic and cook until onion is translucent. 

Add meat to the skillet. Break up any lumps with a fork and cook, stirring occasionally, until meat is evenly browned. 

Stir in kidney beans, tomato puree, tomato paste, green chile, water, 1-ounce of chocolate, ground chili, cumin and beef cube. Mix well.

Bring to a boil, then lower heat and simmer, uncovered, for ½ hour, stirring occasionally. 

Stir in remaining chocolate and continue cooking until thoroughly blended. Taste and adjust seasonings.