As seen on: Giada in Italy, Episode 4. Dino’s Pasta Factory.

Heat the oil in a heavy large frying pan over medium heat. Add the pancetta and sauté until it is brown and crisp, about 8 minutes. Remove the pancetta from the pan and cool. Add the onions to the pan and cook for 10 minutes or until golden brown and lightly caramelized. Add the garlic and 1/2 teaspoon salt and cook 2 minutes more. Set aside to cool slightly. In a large bowl, whisk the cream, remaining salt, parmesan, the gruyere, lemon zest and eggs to blend.

Meanwhile, bring a large pot of salted water to a boil over high heat. Add the pasta and cook until it is just tender but still firm to the bite, stirring occasionally, about 8 to 10 minutes. Drain reserving 1 cup of pasta water. Add the pasta back to the pan along with the onions, cream mixture, 1/4 cup pasta water and pancetta. Toss over low heat until the sauce coats the pasta thickly adding pasta water as needed, about 2 minutes (do not boil). Season the pasta to taste with pepper. Transfer the pasta to a large wide serving bowl. Sprinkle with chives and serve.