5 ounces guanciale
1 medium onion, peeled and finely chopped
1/4 cup dry white wine
1 pound spaghetti
5 large egg yolks
3/4 cup finely grated Parmigiano-Reggiano
1/3 cup finely grated pecorino Romano
1 teaspoon coarsely ground black pepper
1/4 teaspoon salt

Bring a large pot of salted water to boil.

Cut the guanciale into 1/3-inch dice. Heat a deep, heavy-bottomed, 12-inch skillet over moderate heat. Cook guanciale, stirring, until fat begins to render, 1 to 2 minutes. Add the onion and cook, stirring occasionally, until onion is golden, about 10 minutes. Add the wine and boil until reduced by half, 1 to 2 minutes. Turn off heat.

Cook the spaghetti in boiling, salted water until al dente.

While pasta is cooking, whisk together the egg yolks, grated cheeses, salt and pepper in a small bowl.

Drain spaghetti in a colander and add to guanciale-onion mixture. Turn heat to medium-low and toss pasta with tongs until coated. Remove from heat and add egg mixture, tossing to combine. Serve immediately.

Makes 4 servings.

— Recipe from Boccalone, San Francisco.