Put the lard or the butter with olive oil in a large saute pan, add the onions and a little salt, cover, and cook on very low heat until the onions are very soft, about 1 hour.
Uncover, raise heat to medium-high, and cook until the onions turn a deep, dark gold and any liquid has boiled away.
Add generous black pepper and adjust salt. Add the wine, raise heat, and stir frequently while the wine bubbles away. Stir in the parsley and take the pan off the heat.
Toss with hot drained pasta, adding the Parmigiano-Reggiano as you mix. Separate the onion strands as much as you can so they distribute through the pasta, then serve.