Place a large saucepan over medium heat and melt the butter in the oil. Add the onion, carrot, celery and garlic with a good pinch of salt (about ½ teaspoon) and sauté for 5 minutes, stirring often. Add the diced pancetta and cook for a further 10 minutes, until vegetables are softened and pancetta is golden.
Increase the heat to high and add the meat a third at a time, stirring and breaking lumps with a spoon between each addition. Adding the meat gradually allows the water to evaporate – which is key if you want to brown your meat and not boil it. After the last addition, when no pink can be spotted in the meat and no lumps remain, set a timer to 15 minutes. You want your meat to caramelize and even become crispy in spots. More water will evaporate and flavors will concentrate. You want golden bits of meat to stick to the bottom of your pan – this flavorful crust will then be deglazed with white wine. Watch over your pan as you don’t want your meat to burn. When you see some serious caramelization action happening, lower heat to medium to reach the end of your 15-minute sautéing time (on my stove, that’s after about 8-9 minutes).
Over medium heat, pour the white wine into the sauce pan. With a wooden spoon, scrape all the brown bits stuck to the bottom of your pan. Push the meat all around to make sure you scrape it all off. By the time you’re finished, the wine will be evaporated (2-3 minutes). Be careful not to let the meat stick again (lower the heat if necessary).
Add milk, diced tomatoes (with liquid), beef stock, 1 teaspoon salt and a good grinding of pepper. Bring to a boil and then lower to the lowest heat and let simmer very slowly, half-covered, for 4 hours. Stir once in a while. If your sauce starts sticking before the end of your cooking time, lower the heat (if possible) and/or add a bit of stock or water. In the end, the sauce should be thick, more oil- than water-based and thick like oatmeal. Adjust the seasoning one last time – don’t be afraid of adding more salt (tasting each time you add some), it is this recipe’s key seasoning.
To serve: Reheat the sauce. Mix in a knob or two of butter and about two generous tablespoons of freshly grated parmigiano-reggiano per serving – these last additions will produce an incredibly creamy flavor. Drain your pasta very well and return to the pot. Spoon some sauce, just enough to coat the pasta. Serve in bowls with a few leaves of basil sprinkled on top and more freshly grated parmigiano-reggiano, to taste.