Cook bow tie in a pasta pot of boiling salted water (2 tablespoons salt for 6 quarts water)until al dente. Reserve 1/2 cup cooking water, then drain pasta.
2
Meanwhile, bring cream and butter to a simmer in a 12-inch heavy skillet over medium-low heat, adding 1/4 teaspoon salt and 1/2 teaspoon pepper.
3
Add bow ties, 1/4 cup reserved water and cheese to sauce and toss. Add more cooking water to sauce as necessary.