Cook the pasta in a large pot of boiling salted water until tender but still firm to the bite, stirring occasionally, about 4 minutes. Drain
Stir 2 cups of the cream and the lemon juice
in a heavy large skillet to blend
. Add the butter and cook over medium heat just until the butter melts, stirring occasionally, about 3 minutes. Remove from the heat.
Add the pasta
and toss. Add the remaining 1/2 cup of cream, and Parmesan to the cream sauce
in the skillet. Add the lemon zest
, salt, and white pepper. Toss the pasta mixture over low heat until the sauce thickens slightly, about 1 minute.