Place a heavy bottomed pot such as a dutch oven over medium-low heat and then add the 100 grams pancetta. Once the fat starts to render out, turn up the the heat and fry the pancetta until cooked through and starting to brown.
100 grams pancetta
Add the 400 grams ground beef and 200 grams ground pork and fry, crumbling the meat with a spatula until the meat is cooked through. Transfer the meat to a bowl, leaving behind as much of the fat in the pot as possible.
400 grams ground beef, 200 grams ground pork
Add the 200 grams onions, 120 grams carrots and 100 grams celery and cover with a lid. Turn down the heat to medium low and steam the vegetables for 10 minutes.
200 grams onions, 120 grams carrots, 100 grams celery
Remove the lid, turn up the heat to medium-high, and sauté until the liquid has evaporated and the vegetables start to brown (about 10 minutes).
Add the 1 cup whole milk and then return the meat back into the pot. Simmer the milk until it's mostly evaporated (about 10 minutes), stirring from time to time to prevent burning.
1 cup whole milk
Add the 1 cup dry white wine and continue simmering until most of the wine has evaporated (about 10 minutes).
1 cup dry white wine
Add the 1 cup tomato juice, 2 teaspoons porcini mushroom powder, ¼ teaspoon ground nutmeg, ¼ teaspoon ground black pepper and 1 bay leaf and stir to combine. Cover the pot with a lid and then turn down the heat as low as your stove will go. Simmer covered for 1 ½ hours, stirring occasionally to prevent burning. If the sauce gets too thick and starts sticking to the bottom of the pot, add a bit of water.
1 cup tomato juice, 2 teaspoons porcini mushroom powder, ¼ teaspoon ground nutmeg, ¼ teaspoon ground black pepper, 1 bay leaf
Add the 2 tablespoons tomato paste and continue cooking uncovered for another 30 minutes, stirring frequently to prevent burning.
2 tablespoons tomato paste