Ingredients

• 2 bacon slices, cut into 1-inch pieces
• 1/4 pound spaghetti
• 1/2 tablespoon unsalted butter
• 1/3 cup grated Parmigiano-Reggiano plus additional for serving
• 1 to 2 tablespoons chopped tarragon or parsley
• 1 large egg

Instructions

1. Cook bacon in a 10-inch nonstick skillet over medium heat until crisp. Transfer bacon with a slotted spoon to paper towels to drain.
2. Meanwhile, cook spaghetti in a 4-quart saucepan of salted boiling water until al dente. Reserve 1/3 cup cooking water, then transfer spaghetti with tongs to a small bowl, shaking off excess water, and keep pan of water simmering.
3. Pour off all but 2 teaspoons bacon fat from skillet, then whisk butter into fat in skillet over medium heat. Add spaghetti, reserved cooking water, cheese, and a rounded 1/4 teaspoon pepper and cook, stirring, until sauce is thickened and almost completely absorbed, 2 to 3 minutes. Add bacon and 1 tablespoon tarragon and toss. Season with salt and pepper.
4. Break egg into a cup and gently slide into water. Poach at a bare simmer to desired doneness (we prefer a firm white with a runny yolk, 2 to 3 minutes).
5. Serve pasta topped with egg (transfer using a slotted spoon). Sprinkle with remaining tarragon if desired.