Recipe slightly adapted from Mario Batali.
One last thing to bring up are the cooking times for each step of the process. I've seen quite the range of times throughout various authentic recipes, but my overall opinion that I've gained is that it's hard to overcook the sauce. I've adjusted cooking times below from the original recipe to what I believe is the general consensus out there.
1/4 cup extra virgin olive oil
2 tablespoons unsalted butter
2 medium onions, finely chopped
4 ribs celery, finely chopped
2 carrots, peeled and finely chopped
5 garlic cloves, sliced
1 pound ground pork
1 pound ground veal
4 ounces ground bacon or pancetta
4 1/2 ounces tomato paste
1 cup whole milk
1 1/2 cups dry white wine
1/2 cup fresh parsley, coarsely chopped
1 1/2 pounds fresh taglietelle
1/2 cup freshly grated Parmigiano-Reggiano
In a heavy-bottomed pot, heat the oil and butter over medium heat. Add the onions, celery, carrots, and garlic and season with salt. Cook for about 15 minutes. Add the veal, pork, and bacon/pancetta and cook on high until dark brown stirring often. This should take roughly 45 minutes. [Note that the desired color is darker than you would typically go with when browning similar ground meats].
Add the tomato paste and cook for 10 minutes. Add the milk and cook until almost fully reduced. Lastly, add the wine and bring to a boil. Once boiling, reduce to a simmer and cook for 2 to 3 hours, stirring occasionally. Season to taste, remove from heat, and cool.
At this point, you could either store the bolognese in the refrigerator (for several days) or the freezer (for several weeks/months) if serving on a later date, or proceed to making the pasta.
For the pasta, bring a large pot of water to a boil. Add salt, and then add fresh pasta. Cook the pasta for 1 minute less than typical. Drain the pasta and reserve the pasta water.
To combine, use your best judgement and personal preferences on proportions. For a typical serving of pasta, I combined roughly 3/4 cup of the bolognese with 1/3 cup pasta water and 1/3 cup Parmigiano-Reggiano. Finish with a splash of extra virgin olive oil and garnish with more Parmigiano-Reggiano and some fresh parsley.