In a large pot, bring the water and 1/4 teaspoon of the salt to a boil. Add the pasta and cook until al dente, about 4 minutes. Drain and place in a mixing bowl, add 1/2 cup of the truffle oil, 3/4 cup of the cheese, the remaining 1/2 teaspoon salt, the black pepper, and chives and toss to mix. To serve, garnish with the shaved truffle, drizzle with the remaining 2 tablespoons truffle oil, and sprinkle with the remaining cheese. Serve immediately.