Bring a large pot of water to a boil. Liberally salt the water and cook penne to al dente. Reserve 1/2 cup hot, starchy pasta water before draining pasta.
While the pasta cooks, heat olive oil in a large skillet over medium-high heat. Add guanciale or pancetta and cook until crispy and brown, about 4-5 minutes. Season with black pepper and add garlic. Cook until garlic is slightly brown.