In a large, heavy skillet, heat the EVOO, 3 turns of the pan, over high heat. Add the pancetta and cook until browned, 2 to 3 minutes. Using a slotted spoon, transfer to a small bowl; reserve the skillet.
On a plate, mix the flour and allspice. Season the pork with salt and pepper and coat with the flour, shaking off any excess. Add the pork to the reserved skillet and cook over medium-high heat until browned, about 5 minutes; transfer the pork to a plate. Add the onion, carrots, celery, bay leaf and rosemary to the skillet and cook until the vegetables are softened, about 7 minutes. Stir in the wine, scraping up any browned bits on the bottom of the pan, and bring to a boil. Stir in the tomato paste, then 2-1/2 cups chicken broth. Add the browned pork and simmer over medium-low heat until thickened, 10 to 12 minutes. Discard the bay leaf and rosemary sprig.
Meanwhile, in a medium saucepan, bring the remaining 1-1/2 cups chicken broth and the milk just to a boil. Whisk in the polenta and cook until thickened, 3 minutes. Remove from the heat and stir in the cheese, butter and sage; season with salt and pepper.
Pour the stoup into bowls and top with a dollop of polenta and some pancetta.