Heat heavy large pot over medium heat. Add pancetta and bacon and sauté until crisp. Using slotted spoon, transfer pancetta to paper towels to drain. Sprinkle with salt and pepper.
Working in batches, brown ribs in drippings in pot over medium-high heat until brown on all sides, about 8 minutes per batch. (if the pancetta and cheeks don’t release enough fat, add some olive oil to the pot to brown the remaining cheeks) Transfer to a plate.
Add onions and next 4 ingredients to pot. Cover, reduce heat to medium, and cook until vegetables are soft, stirring occasionally, about 10 minutes. Add wine. Boil uncovered until liquid is reduced by half, scraping up browned bits, about 5 minutes.
Add broth, tomatoes, parsley, thyme, bay leaf, and pancetta. Return ribs to pot, cover partially, and simmer 1 hour. Uncover and simmer until meat is tender, stirring occasionally, about another hour longer.
Transfer cheeks to plate; discard bay leaf. Spoon fat from surface of sauce. At this point you may want to puree the sauce. Add chocolate, cocoa powder, rosemary and chipotle pepper; stir until chocolate melts. Season to taste with salt and pepper. Return ribs to pot. Simmer to rewarm, about 5 minutes.