Ingredients:

  • 1 cup (226g) Unsalted Butter, chilled and cubed
  • 1 cup (240ml) Heavy Cream (35% fat)
  • 1 ½ cups (about 150g) Parmigiano-Reggiano Cheese, finely grated
  • 2 cloves Garlic, minced very finely (optional)
  • ½ teaspoon Freshly Ground Black Pepper, or to taste
  • Salt, to taste
  • ½ cup (120ml) reserved Pasta Cooking Water

Instructions:

  1. Cook pasta in heavily salted boiling water until just shy of al dente (about 1 minute less than package directions). Crucially: Reserve at least ½ cup of the starchy cooking water before draining.
  2. While the pasta cooks, gently melt half of the chilled butter (½ cup) in a large, heavy-bottomed sauté pan over low heat. Add minced garlic (if using) and cook gently for 30 seconds until fragrant—do not let it brown.
  3. Pour in the heavy cream and bring the mixture barely to a simmer (tiny bubbles around the edge). Immediately reduce heat to the absolute lowest setting.
  4. Remove the pan from the heat entirely for 30 seconds. Gradually whisk in the remaining cold butter, one cube at a time, until it is fully incorporated and the sauce looks slightly thickened.
  5. Return the pan to very low heat. Vigorously whisk in the finely grated Parmigiano-Reggiano, a handful at a time. The sauce must not boil once the cheese is added, or it will separate and become grainy. Whisk constantly until smooth and glossy.
  6. Whisk in the reserved pasta water, 1 tablespoon at a time, until the sauce reaches a luscious, clinging consistency that coats the back of a spoon. Season generously with black pepper and taste for salt.
  7. Immediately toss the drained, slightly undercooked pasta directly into the sauce. Toss rapidly for 1 minute off the heat to allow the pasta to absorb the sauce and finish cooking perfectly. Serve immediately with extra grated cheese on top.