For The Ragù:

3 oz. (6 Tbs.) unsalted butter
1/4 cup extra-virgin olive oil
2 medium celery stalks, finely chopped (1-1/3 cups)
2 medium carrots, peeled and finely chopped (2/3 cup)
2 small yellow onions, finely chopped (1-1/3 cups)
1 lb. boneless beef brisket or chuck, finely diced or ground (2 cups; see tip)
1 lb. boneless pork shoulder, finely diced or ground (1-1/2 cups; see tip)
8 oz. pancetta, finely diced (1-1/4 cups)
2 cups dry red wine
1/2 cup canned tomato purée
1/4 cup tomato paste diluted in 1/2 cup water
2 cups homemade or low-salt canned beef or chicken broth; more as needed
1 cup whole milk
Kosher salt and freshly ground black pepper

Tip:
To chop the ragù meat, cut each piece into 1/4-inch slices, Then cut the slices into thin strips lengthwise and and dice the strips crosswise. Alternatively, you can pulse the meat in food processor, but be careful not to chop it too finely or into a paste.
To assemble:

3/4 lb. fresh lasagne noodles (store-bought or homemade)
1/2 oz. (1 Tbs.) unsalted butter, cut into small cubes, plus more for the pan
1 cup freshly grated Parmigiano-Reggiano
Double recipe of Basic Cream Sauce

Tip:
If time is short and you can't find fresh pasta sheets in your local stores, use 1 lb. good-quality dried lasagne noodles, cooked according to package instructions.