Boil the potatoes in plenty of water until tender (but not absorbing water).

Meanwhile, heat the butter over medium-low heat and add the onion and garlic. Sweat low heat until the aromatics are soft and translucent. Set aside.

Drain the potatoes, allow to cool a few minutes, then pass through a food mill or ricer. To the potatoes, add the onion, garlic, Parmigiano, mortadella, stracchino, herbs, and salt and pepper to taste. If necessary to moisten the mixture, add the egg. Set aside.

Roll the pasta out to the thinnest setting on a pasta rolling machine and cut the sheet into rectangles 3 inches by 1-inch. In the center of half the rectangles, place a scant tablespoon of the potato mixture. Top the filled rectangles with the unfilled rectangles and press at the edges to seal.

Bring 6 quarts of water to a boil and add 2 tablespoons salt.

Warm the Ragu Bolognese in a 12 to 14-inch saute pan over medium-high heat.

Cook the pasta in the boiling water for 3 minutes. Drain and add to the pan with the ragu. Add the remaining butter and toss over high heat 1 minute to coat. Divide the pasta evenly among 6 warmed pasta bowls, top with grated Parmigiano-Reggiano, and serve immediately.

Mound 3 1/2 cups of the flour in the center of a large wooden cutting board. Make a well in the middle of the flour and add the eggs and the olive oil. Using a fork, beat together the eggs and oil and begin to incorporate the flour, starting with the inner rim of the well.

As you expand the well, keep pushing the flour up from the base of the mound to retain the well shape. The dough will come together when half of the flour is incorporated.

Start kneading the dough with both hands, using the palms of your hands. Once you have a cohesive mass, remove the dough from the board and scrape up and discard any leftover bits. Lightly reflour the board and continue kneading for six more minutes. The dough should be elastic and a little sticky. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature. Roll or shape as desired.

In a 6 to 8 quart, heavy-bottomed saucepan, heat olive oil and butter over medium heat. Add onion, celery, carrot, and garlic and sweat over medium heat until vegetables are translucent. Add veal, pork, beef, and pancetta and stir into vegetables. Brown over high heat, stirring to keep meat from sticking together. This should take 15 to 20 minutes. Add tomatoes and simmer 15 minutes. Add the milk and simmer until reduced to nothing, about 10 minutes. Add the wine and brodo, bring to a boil, lower the heat, and simmer over for 2 to 21/2 hours. Season with salt and pepper, to taste and remove from heat.