Prepare your vegetables: Cut the onion, carrot, and celery into big chunks. If you have a food processor or high-powered blender, pulse the onion, carrot, celery, and garlic (if using) in the machine until they're chopped into very small pieces, ranging from couscous to pea-sized. If you don't have a machine, just continue to run your knife back and forth over the mix of vegetables, adding the garlic, until they're chopped very small.

Build the base flavor: Heat a medium/large heavy pot or Dutch oven (4- to 5 quarts) over medium-high heat. If using pancetta, add it to the pan dry and let it cook and crisp, rendering a puddle of fat. If you're not using pancetta, coat the bottom of the pan with the olive oil and let it warm up. For both approaches, add the vegetables and season them generously with salt and pepper, and add a pinch or two of pepper flakes. Cook the vegetables until they are evenly brown, stirring frequently and not fretting if they stick, it will all work out, about 10 minutes. Add your ground beef, season it generously with salt and pepper, and cook it until it's very well-browned, about 10 minutes. Add the milk and cook it until it has disappeared, 3 to 4 minutes, scraping up any stuck bits. Add the wine and do the same. Add the tomato paste and cook it for 3 to 4 minutes. Add 2 cups of water, a bay leaf, and nutmeg and bring to a simmer, then reduce heat to medium-low.

Cook the ragú: Here's how the next 3 hours (or more) hours will go: You'll keep a carafe of water near the stove. You'll stir the sauce from time to time, I find checking in every 30 minutes is about right. As the water in the sauce cooks off, you'll want to add more but you don't want to add more than 1 cup at a time or you'll end up boiling the meat rather than creating a thick, robust ragú. Taste it from time to time and add more seasoning if needed. Simmer for 3 hours — longer if you wish, but I promise that 3 solid hours will suffice. Remove and discard the bay leaf.

To finish: Cook your pasta to 1 to 2 minutes shy of done in well-salted water. Before you drain it, ladle 2 cups cooking water into your carafe. Drain the pasta and add it directly to the ragú, along with 1/2 to 1 cup of the reserved water. Cook the pasta and sauce together for 1 to 2 minutes, adding more pasta water if needed to keep it moving. Serve in wide bowls.

Do ahead: If you don't want to use all of the bolognese right now, it freezes fantastically in a bag with any extra air pressed out. Defrost in the fridge and bring back to a simmer in the same pot; you'll usually need a couple extra splashes of water to loosen it.