Bring a large pot of salted water to a boil. Cook pasta according to package instruction. Drain, reserving about ½ cup of pasta water for finishing sauce.
In a large serving bowl, whisk together mascarpone, lemon zest, lemon juice, oil, thyme, Parmigiano, salt and pepper.
Add hot pasta to the cheese mixture. Toss well to coat and serve.
Note: Add hot pasta-cooking water if necessary for desired consistency.