In a large pot, bring salted water to a boil, and add your fettuccini. Cook according to package instructions, typically around 8–10 minutes, until al dente. Reserve about a cup of pasta water, then drain and set aside.

While the pasta cooks, grab a food processor and add the fresh parsley, grated Parmesan cheese, lemon juice, salt, and white pepper. Pulse until finely chopped, about 20–30 seconds.

With the food processor running, slowly drizzle in the olive oil and continue processing until smooth, about 30 seconds. Taste and adjust seasoning.

In a large mixing bowl, toss the drained fettuccini with the pesto. Stir well, adding reserved pasta water a little at a time to achieve desired creamy consistency.

Plate your parsley pesto pasta, garnishing with extra grated Parmesan if desired. Serve immediately while warm and fresh.