In a dutch oven cook the pancetta over medium heat - tossing occasionally until browned (not crispy). Add carrot, onion, garlic and pepper flakes - increase heat to medium-high. Cook until veggies are tender. Add lamb, salt and black pepper - cook until the meat is browned - breaking it up. Drain excess fat.
Stir in the red wine, bay leaves and thyme - bring to rapid simmer. Cook stirring until wine reduces and there is only a small amount of liquid. Add marinara and bring to boil. Reduce heat to light simmer until sauce has thickened - maybe 20-30 minutes.
Discard the bay leaves and stir in the milk - for 10 more minutes.