Heat vegetable oil in a large Dutch oven over medium-high heat and brown the brisket cubes in batches until well-seared on all sides, about 10 minutes total, then set aside.
In the same pot, brown the ground pork, breaking it up with a spoon, about 6 minutes, then add onions and cook until softened, about 5 minutes.
Add garlic and cook for 1 minute, then stir in all the spices (chili powder, cumin, paprika, oregano, cinnamon, and cloves), cooking for 1 minute until fragrant.
Return the brisket to the pot and add crushed tomatoes, beef broth, beer, tomato paste, cocoa powder, salt, pepper, and bay leaves, stirring well to combine.
Bring the mixture to a boil, then reduce heat to the lowest possible setting, cover with a lid slightly ajar, and simmer for 10 hours overnight, checking once or twice if possible.
In the morning, remove bay leaves and skim any fat from the surface if desired.
Taste and adjust seasoning, then simmer uncovered for 30 more minutes if you want it thicker, or serve immediately with your favorite toppings.