Place the whole black peppercorns in a large, dry skillet over medium heat. Toast for 1-2 minutes, stirring frequently, until fragrant. Transfer the peppercorns to a mortar and pestle or spice grinder and crush them coarsely.

Bring a large pot of water to a boil and salt it generously. Add the spaghetti and cook according to package directions until al dente. Use less water than you normally would to ensure it becomes extra starchy.

While the pasta cooks, add the freshly grated Pecorino Romano and about two-thirds of the crushed black pepper to a large mixing bowl. A few minutes before the pasta is done, ladle about 1/2 cup of the hot, starchy pasta water into the bowl. Whisk vigorously to create a thick, creamy paste.

Using tongs, transfer the al dente pasta directly to the skillet. Add a splash of pasta water. Pour the cheese paste over the pasta and toss vigorously off the heat until a glossy sauce forms. Add more pasta water as needed to reach desired consistency.

Divide the pasta among warm bowls. Garnish with the remaining crushed black pepper and an extra sprinkle of Pecorino Romano. Serve immediately.