Cook the pasta in a large pot of generously salted boiling water (1 tablespoon of salt for every 6 cups of water) until tender but still firm to the bite, stirring occasionally.
Drain, reserving 1/2 cup of the pasta cooking water. Return drained spaghetti to the pot.
Meanwhile, whisk the lemon juice, oil, heavy cream, Parmesan, and red pepper flakes in a bowl to combine. Add ¼ cup of the pasta cooking water and whisk to combine.
Add lemon sauce to spaghetti in pot; toss until pasta is evenly coated with sauce. Add remaining cooking liquid, if necessary. Season with salt and pepper, to taste.
Garnish with lemon zest, chopped basil (if desired) and parmesan cheese. Serve immediately.
Video
Notes
I like to cook my pasta about a minute less than the package directions call for. This ensures that your pasta remains al dente as it's tossed with with the lemon cream sauce and heated through. This creamy lemon pasta will keep in the refrigerator for up to three days. Reheat leftovers in the microwave, or in a skillet, adding in a splash more water, chicken broth, or cream.