Bring a large pot of water to a boil. Add the kosher salt and return to a rolling boil. Add the bucatini pasta and cook until al dente according to the package directions. Don’t overcook the pasta.
When the pasta is about halfway done cooking, start making the sauce. In a large skillet, melt the unsalted butter over medium-high heat. Add the black pepper and stir, cook for about 2 minutes.
Add ½ cup of the pasta water from the pasta pot and bring to a simmer. Stir and cook for 1 minute.
Before you drain the pasta, reserve ½ cup of the pasta water. Use a colander to drain the pasta. Add the pasta, Parmesan cheese, and Pecorino cheese to the skillet, make sure the heat is off. Using tongs, toss until the all of the cheese is melted and until all of the pasta noodles are well coated.
Add the remaining ½ cup of pasta water and turn the heat on low. Cook for 1 minute or until the water mixes into the pasta.
Transfer the pasta to plates or bowls and garnish with additional cheese, if desired. Serve immediately.
