Stir the oil, parsley, lemon juice and lemon peel in a large serving bowl. Add the cooked pasta and toss with enough reserved pasta water, 1/4 cup at a time, to moisten. Season the pasta with salt and red pepper flakes, to taste. Sprinkle grated lemon peel over pasta for extra flavor and texture. Sprinkle with the Parmesan and serve.
Remove from heat. Cool to room temperature, about 2 hours. Transfer the oil and pepper flakes to a 4-ounce bottle. Seal the lid. Refrigerate up to 1 month.
Yield: 2 cups
Prep Time: 2 minutes
Cook Time: 5 minutes
Inactive Prep Time: 2 hours