Bring a large pot of water to a boil for the pasta. When boiling rapidly, salt the water and cook the pasta to al dente. Heads up: reserve 1/2-3/4 cup of the starchy cooking water just before draining the pasta.
Heat a large skillet over medium heat with the EVOO, three turns of the pan. Add the pancetta, season with black pepper and brown lightly. Stir in the garlic, chili pepper (if using), and the whites of the scallions, then zest the lemon over the pan and stir in the thyme. Stir for 2-3 minutes, then add the wine, a couple turns of the pan, and reduce by half, 1-2 minutes. Reduce the heat to low.
When the pasta is about ready, beat the egg yolks with the reserved starchy water to temper them. Add the lemon juice, parsley and the greens of the onions to the pan.
Drain the pasta and add it to the pan. Turn off the heat, pour in the tempered eggs and sprinkle in a small handful of each of the cheeses. Toss vigorously for 1-2 minutes, until the sauce coats the pasta and it’s thick and shiny. Serve in shallow bowls with a little extra cheese, shredded basil and diced yellow tomatoes on top.