In a large pot bring 6 quarts water to a boil. Using a ladle, fill four individual serving bowls with about 1/2 cup of the boiling water each; set the bowls aside to warm.

In a 3- to 4-quart saucepan, bring 1/2 cup of the half-and-half, nutmeg, and 1/4 teaspoon salt to a simmer. In a small bowl, whisk the cornstarch and remaining 1/4 cup half-and-half together, then whisk it into the simmering mixture. Continue to simmer, whisking constantly, until thickened, about 1 minute. Cover and remove from heat.

Stir 1 tablespoon salt and the fresh pasta into the boiling water and cook, stirring constantly, until al dente, 1 to 2 minutes (about 12 minutes for dry pasta). Reserving 3/4 cup of the pasta cooking water, drain the pasta.

Return the half-and-half mixture to medium-low heat and whisk in 1/2 cup of the reserved pasta cooking water. Slowly whisk in the Parmesan. Add the pasta and cook, coating the pasta evenly with the sauce, until the sauce has thickened slightly, about 1 minute. Season with pepper to taste. Working quickly, empty the serving bowls of water, divide the pasta among the bowls, and serve immediately.