Bring a large pot of water to a boil over medium-high heat. Cook 4 ounces diced pancetta in a large nonstick skillet over medium heat until it starts sizzling and releasing fat, 2 to 4 minutes. Reduce the heat to medium-low and cook, stirring occasionally, until browned and crisp, 6 to 8 minutes more. Stir in ¾ teaspoon coarsely ground black pepper.

When the pancetta is almost ready, add 1 pound potato gnocchi and 1 teaspoon kosher salt to the boiling water. Cook according to package directions until the gnocchi float, 2 to 3 minutes.

Using a slotted spoon, transfer the gnocchi to the skillet and reserve the cooking water. Cook the gnocchi, stirring until well-coated with the pancetta and pepper drippings, for 1 to 2 minutes. Stir in ⅓ cup of the gnocchi cooking water and remove the skillet from the heat.

Whisk 1 large egg, 1 large egg yolk, ¾ ounce finely grated Pecorino Romano cheese, and ½ ounce finely grated Parmesan cheese together in a medium bowl until thick and combined.

While stirring constantly, add the egg and cheese mixture to the skillet in 2 batches, stirring constantly, until the sauce is smooth and glossy. If needed, return the skillet to low heat, stirring constantly and adding cooking water a tablespoon at a time if needed, until the sauce thickens. Garnish with chopped fresh parsley leaves and more black pepper if desired.