In a large Dutch oven or heavy-bottomed pot, cook the chopped bacon over medium heat until crispy. Remove the bacon with a slotted spoon and set aside, leaving the rendered fat in the pot.

Sear the beef chuck in batches in the bacon fat until browned on all sides, then remove and set aside. Next, sauté the chopped onion in the same pot until softened, about 5-7 minutes, followed by the minced garlic for 1 minute until fragrant.

Return the seared beef to the pot, then add all the chili powder blend ingredients, other seasonings like salt, pepper, and cayenne if using, to the pot. Stir well, ensuring the beef is thoroughly coated with the spices.

Pour in the beef broth and crushed tomatoes, bringing the mixture to a simmer. Reduce the heat to low, cover the pot, and let it simmer for at least 2-3 hours, or until the beef is fork-tender, stirring occasionally.

Remove the lid from the chili, and if it appears too thin, whisk in the masa harina to thicken. Simmer for another 15-20 minutes, allowing the flavors to meld and the chili to reach its desired consistency.

Stir in the reserved crispy bacon just before serving. Serve hot with your favorite toppings such as shredded cheese, sour cream, or fresh cilantro.