2 tablespoons unsalted butter, at room temperature
1 cup freshly grated Parmigiano-Reggiano cheese (3 ounces)
Salt and freshly ground pepper
Cook the rigatoni in a large pot of boiling salted water, stirring occasionally, until al dente; drain and return to the pot.
Meanwhile, warm the cream in a small saucepan over low heat. Add the butter to the rigatoni and toss well, then add the cream and cheese and toss to coat. Season with salt and pepper, transfer to a warmed bowl and serve.