For the meat sauce, heat EVOO, 2 turns of the pan and melt in butter. Add pancetta, render 2 minutes then add beef and sausage (and liver, if using). Brown 12-15 minutes then add onions, bay, thyme, nutmeg, garlic, salt, pepper and rosemary, and cook 10 minutes more. Add wine and let it absorb; add tomatoes and simmer 30-40 minutes.
Cook pasta 5 minutes in salted boiling water. Reserve 1 cup starchy cooking water then drain and run pasta under cold water to cool.
Combine ricotta, mozzarella, eggs, Parm, parsley, salt and pepper in bowl.
For the béchamel, heat a saucepot over medium heat, add butter and melt. Whisk in flour then milk, season with salt, white pepper and nutmeg to taste, lower heat and add cream. Cook to thicken slightly.
Preheat oven to 375°F.
Toss pasta with all of the meat sauce and reserved cooking water. Pour half into a lasagna pan or baking casserole then top with ricotta mixture. Add remaining pasta and meat sauce, and top casserole with béchamel and Parm. Bake to brown and bubbly.