Heat the dried peppers in a pot. Add 2 cups chicken stock and simmer at a low bubble until tender, 10 minutes. Seed the peppers.
Puree the chipotle in adobo sauce in a food processor. Remove all but about 2 round tablespoons to a plastic bag and freeze for another use. Add the softened dried peppers and their broth to the food processor along with the oregano, coriander and cinnamon. Puree until smooth.
Meanwhile, sprinkle the pork with salt and pepper. Heat 2 tablespoons EVOO in a Dutch oven over medium-high heat, add the pork, brown and then remove. Add another turn-of-the-pan of oil, onions and garlic and stir to soften. Return the pork to the pan, add the pepper puree, the remaining stock and about 1 quart water to raise the liquid level halfway up the pork. Bring to a boil, and then reduce the heat and simmer over medium-low heat, partially covered, for 2 to 2 1/2 hours until very tender.
Remove the pork, cool to handle, shred and return to the sauce. Bring back to a simmer and reduce to thicken, 15 minutes. For a make-ahead meal, remove from the heat, cool and cover, store in the fridge. Reheat over medium heat, stirring frequently.
To serve, while the pork reheats, place the rack in center of the oven and turn the broiler on high or the oven to 500 degrees F.
Place the milk in a pot and warm to a low bubble over medium heat while you bring 3 cups water to a full boil in a tea kettle or another pot. Add the cornmeal to the milk and whisk in the boiling water, fennel pollen and about 1 1/2 teaspoons kosher salt. Whisk constantly for 15 minutes. Remove from the heat and stir in the butter.
Place the pork in a casserole or individual ovenproof bowls. Top with cornmeal about 1-inch thick and sprinkle with the cheese. Place in the broiler or oven to set and brown the top, a few minutes for individual bowls, 10 to 15 minutes for a large casserole.