Adapted from Francine Segan. The original recipe called for Red Delicious apples, but in my opinion you should use a firm, sweet apple that was recently picked (if possible)--and if it has not been recently picked I would avoid Red Delicious because I don't think they last on supermarket shelves worth a darn. Fuji would be a nice choice if you have no local options.
Boil the pasta according to directions in salted water. Cook until al dente, at which point drain, reserving 1/4 cup of the cooking water.
While the pasta is cooking, choose a skillet large enough to toss all of the ingredients in, including the pasta. Heat the skillet over medium heat with the extra virgin olive oil.
Add the guanciale and cook for 5 minutes, moving around the pan occasionally.
Add the onions with a pinch of salt. Cook for about 5 minutes, stirring, and then raise the heat to high and cook another 3-4 minutes.
Add the apples, wine and rosemary, and use the wine to deglaze the bottom of the pan, scraping up all the tasty bits.
Cook on high until the wine evaporates, about 1 minute boiling briskly.
Season with freshly ground black pepper (remember that the guanciale also has black pepper so do not go crazy) and coarse sea salt.
Add the pasta to the pan along with 1/4 cup of the pasta cooking water. Toss and cook for 1 minute, letting the pasta water boil off and become absorbed.
Remove the rosemary sprig if desired. Serve and top individual servings with grated pecorino romano. Garnish with fresh rosemary sprigs if desired.