Eggs and cheese combine to form a simple yet rich sauce.
Whisk together eggs and cheese in a large bowl until combined, and season with salt and pepper. Cook bacon in a medium skillet over medium-high heat, stirring occasionally, until crisp, 6 to 8 minutes. Transfer to a paper-towel-lined plate to drain.
Meanwhile, bring a large pot of generously salted water to a boil. Add pasta and cook until al dente. Reserve 1 cup pasta water, and then drain pasta. Transfer pasta to bowl with egg mixture, tossing to combine. Add lemon zest, juice, and frisee and toss to combine, adding enough pasta water to form a smooth sauce that coats pasta. Season to taste with salt and pepper and top with bacon. Serve immediately.