Step 1: Prepare the Ingredients

1. Slice the Guanciale: Cut the guanciale into thin strips or small cubes. This ensures even cooking and maximum flavor release.
2. Grate the Cheese: Finely grate the Pecorino Romano cheese using a microplane or fine grater. This will help it melt smoothly into the sauce.

Step 2: Boil the Pasta

1. Fill a large pot with water, season generously with salt, and bring it to a boil. The water should taste like the sea, as this is the only seasoning for the pasta itself.
2. Add the spaghetti and cook it until just shy of al dente, about 1-2 minutes less than the package instructions. Reserve 1 1/2 cups of starchy pasta water before draining.

Step 3: Cook the Guanciale

1. Heat a large, heavy-bottomed skillet over medium heat. Add the guanciale to the skillet and cook, stirring occasionally, until it turns golden brown and crispy, about 5-7 minutes.
2. Once the guanciale is crispy, remove it with a slotted spoon and set it aside, leaving the rendered fat in the skillet.

Step 4: Make the Sauce

1. Reduce the heat to low and add 1 teaspoon of freshly ground black pepper to the rendered fat in the skillet. Toast the pepper for about 30 seconds to release its aroma.
2. Add 1/2 cup of the reserved pasta water to the skillet, stirring to combine with the rendered fat. The mixture should emulsify into a glossy sauce.

Step 5: Combine Pasta and Sauce

1. Add the cooked spaghetti to the skillet and toss it in the sauce over low heat. Add more reserved pasta water as needed to coat the pasta evenly and prevent sticking.
2. Gradually sprinkle the grated Pecorino Romano cheese over the pasta, tossing constantly to create a creamy sauce. Add small amounts of pasta water if the sauce becomes too thick.

Step 6: Serve

1. Remove the skillet from the heat and stir in the crispy guanciale. Taste and adjust the seasoning with more black pepper if desired.
2. Divide the pasta among serving plates and garnish with additional Pecorino Romano cheese and black pepper. Serve immediately and enjoy!