01 -
Bring a large pot of generously salted water to a rolling boil. Add spaghetti and cook until al dente (firm to the bite). Reserve 1 cup of pasta cooking water before draining.
02 -
Heat a large skillet over medium heat. Add the diced pancetta and cook until golden and crispy, about 5-7 minutes. Remove the skillet from heat but retain the rendered fat in the pan.
03 -
In a mixing bowl, whisk together the egg yolks, whole egg, grated Pecorino Romano, grated Gruyère, and a generous amount of freshly cracked black pepper. Stir in a tablespoon of hot pasta water to slightly temper the eggs.
04 -
Add the hot drained spaghetti directly to the skillet with pancetta (keeping off the heat). Toss to coat with the rendered fat. Quickly pour in the egg-cheese mixture and stir vigorously, adding small splashes of reserved pasta water as needed to create a glossy sauce that coats each strand. The residual heat should gently cook the eggs without scrambling them.
05 -
Transfer to warmed plates and finish with additional black pepper and extra grated cheese if desired. For extra richness, drizzle with a small spoonful of reserved pancetta fat.