In a large heavy saucepan, heat oil. Saute onion and garlic until soft but not brown. Add beef and sausage. Cook until brown; pour off fat. Add liquid from the tomatoes. Chop tomatoes and add to meat mixture with tomato paste, chili powder, cumin, oregano, baked beans, salt, sugar, and cocoa powder. Simmer partially covered for 2 hours, stirring often. If too dry, add a little water as it cooks.