4 tbsp. extra-virgin olive oil
4 oz. thinly sliced cured hog jowl, bacon or pancetta cut into 1⁄2″ pieces
Hanful of green peas or baby lima beans (optional)
2 tsp. freshly cracked black pepper, plus more to taste
1 3⁄4 cups finely grated Parmesan
1 egg plus 3 yolks
Kosher salt, to taste
1 lb. spaghetti
 
Heat oil in a 10″ skillet over medium heat. Add bacon and cook, stirring occasionally, until lightly browned, 6–8 minutes. Add pepper and peas (if using) and cook, stirring occasionally, until fragrant, 2 minutes more. Transfer bacon mixture to a large bowl and let cool slightly; stir in 1 1⁄2 cups Parmesan and egg and yolks and stir to combine; set aside.
Meanwhile, bring a 6-qt. pot of salted water to a boil. Add pasta; cook until al dente, 8–10 minutes. Reserve 3⁄4 cup water; drain pasta and transfer it to guanciale mixture. Toss, adding pasta water a little at a time to make a creamy sauce. Season with salt and pepper; serve with remaining Parmesan.