Bolognese Sauce (The Best)

Ingredients

• • 1 onion, cut into pieces
  • 1 stalk celery, cut into pieces
  • 2 carrots, cut into pieces
  • 2 cloves garlic, cut into pieces
  • 4 oz (115 g) mild pancetta, cut into small pieces
  • 1 oz (30 g) mortadella, cut into small pieces
  • 2 tbsp butter
  • 1 lb (454 g) medium lean ground beef
  • ½ lb (225 g) lean ground veal
  • ½ lb (225 g) lean ground pork
  • ½ cup (125 ml) red wine
  • 1/3 cup (75 ml) tomato paste
  • 2 cups (500 ml) chicken broth
  • 2 bay leaves
  • 2 tsp chopped fresh herbs (sage, marjoram or thyme)
  • 1 pinch red pepper flakes
  • ½ cup (125 ml) milk
  • Salt and pepper