Combine tomatoes and stock in a saucepan over low heat.
Heat butter and oil in high sided-pan or Dutch oven. Add onions and saute until soft and translucent with a sweet aroma, about 5 minutes. Add the celery and saute 1 minute. Add the carrots and saute another minute.
Add pancetta and saute 1 minute.
If using chicken liver, move the vegetables to the side of the pan and add the chicken liver, flatten and stir into it completely changes color and cooked through. Mix back in with the vegetables.
Turn heat to high. Add 1/3 of ground beef, flatten and stir continuously, until any liquid has evaporated. Add another 1/3 of ground beef and repeat. Lastly, repeat with the remaining 1/3 of ground beef.
Drizzle 1/4 cup wine around the edges of the pan. Then repeat with the second 1/4 cup and cook until the alcohol smell dissipates and smells sweet.
Add the milk slowly, in 2 to 3 doses, stirring to incorporate. Season with salt and pepper and a few gratings of nutmeg.
Add tomatoes and broth and simmer for at least 2 hours, stirring often.