Pork Ragu made with leftover pork shoulder roast

Ingredients

• 2 cups whole milk, more as needed
• Kosher salt
• 1 cups yellow stone-ground cornmeal (polenta)
• ¼ cup freshly grated Parmigiano-Reggano cheese, more for sprinkling
• 1½ Tbs. unsalted butter, divided
• 2 Tbs. extra-virgin olive oil
• 2 medium carrots, cut into small dice
• 2 medium celery ribs, cut into small dice
• 1 medium yellow onion, cut into small dice
• pinch of crushed red pepper flakes (optional)
• 3 canned tomatoes, drained and cut into medium dice
• 3 garlic cloves, finely chopped
• 3 cups leftover shredded Slow-Roasted Pork Shoulder
• 3 cups lower-salt chicken broth
• freshly ground black pepper
• 2 Tbs. chopped fresh flat-leaf parsley