Roast poblano chiles over an open flame on a gas stove or grill until the skin is black and charred on all sides, turning often, 10 to 15 minutes.
Place the charred chiles in a plastic bag or in a large bowl covered with plastic wrap. Allow to sit for 5 to 10 minutes, then open and peel off the skin. Cut a slit in each chile lengthwise and remove the seeds.
Heat olive oil in a large pot over medium heat. Add onion and garlic and cook until soft and translucent, 3 to 4 minutes. Add ground pork and cook until browned, breaking up with a spoon while cooking, about 7 minutes. Mix in tomatoes, plantain, apple, peach, parsley, candied orange peel, pine nuts, raisins, almonds, cloves, salt, and pepper. Simmer until filling is cooked through and flavors are well combined, about 10 minutes.
Combine walnuts, milk, goat cheese, sugar, and cinnamon stick in a blender; blend until walnut sauce is smooth and creamy.
Fill each poblano chile with the pork filling and place on a plate. Spoon walnut sauce over chile and sprinkle with pomegranate seeds and parsley.