Render the pancetta: Place diced pancetta and butter in a cold heavy Dutch oven or cast-iron pot. Set over medium-low heat. Cook, stirring occasionally, until the fat has fully rendered and the pancetta is soft but not crispy, 5–7 minutes.

Build the soffritto: Add all diced vegetables to the pot. Reduce heat to low. Cook, stirring every few minutes, until completely softened and nearly translucent, at least 15 minutes. Do not rush this step: the soffritto is the flavor foundation.

Remove soffritto: Transfer soffritto to a bowl and set aside. This allows the meat to make direct contact with the hot pan.

Brown the meat in batches: Increase heat to medium-high. Add meat in 3 separate batches, pressing each against the pan. Allow each batch to brown fully before breaking it up. Continue until all meat is deep brown with no pink remaining.

Return soffritto: Add the reserved soffritto back to the pot. Stir to combine with the meat. Cook together for 2–3 minutes.

Deglaze with wine: Pour in the white wine. Scrape up any browned bits from the bottom of the pot. Cook over medium heat until the alcohol has fully evaporated, 3–4 minutes. The sharp wine smell should be completely gone.

Add tomato: Stir in the passata and tomato paste. Season with salt and pepper. Stir to combine fully. The sauce should look brick-red, not bright red: meat forward, not tomato forward.

Long simmer: Reduce heat to the lowest possible setting. Place lid slightly ajar (about 1 finger width of opening). Simmer for a minimum of 2 hours, ideally 3–4 hours. Stir every 30–40 minutes. If the bottom begins to look dry, add a ladleful of warm beef broth.

Finish with milk: In the last 20 minutes of cooking, pour in the whole milk. Stir to incorporate. The sauce will become silkier and slightly lighter in color. This step softens residual acidity and rounds out the flavor.

Check seasoning and consistency: The finished ragù should be thick, glossy, and dark. If you lift a spoon and the sauce falls slowly in a ribbon, it's ready. Adjust salt and pepper.