Bring a large pot of salted water to a boil. Meanwhile, cut pancetta into ¼-inch batons. In a medium bowl, whisk together egg yolks, grated cheeses, 1/3 cup water, and generous pinch salt and pepper. In a medium nonstick skillet, combine pancetta and oil; cook over medium heat, stirring frequently, until browned, about 15 minutes.
About halfway through pancetta cooking time, cook pasta in the boiling water until al dente (ideally pancetta and pasta will be ready at about the same time). Reserving ¼ cup of the pasta cooking liquid, drain pasta and return to pot. Add pancetta and its rendered fat; toss to combine. Immediately add egg mixture and 2 tablespoons pasta cooking liquid; quickly stir to combine. Moisten with additional pasta cooking liquid, if desired. Serve immediately, passing cheese and pepper at the table.
Serves 4-6 - or two very, very hungry people... ; )