In large pot of boiling, salted water, cook bow ties per package directions.
In a food processor, combine artichoke hearts, lemon juice, Parmesan, and walnuts, and process for 30 seconds. Slowly drizzle in olive oil until mixture becomes a thick paste. Transfer pesto to a large bowl. Season, to taste, with salt and pepper.
Drain pasta and add to pesto in bowl. Toss to coat. Serve hot with grated Parmesan.
Recipe courtesy of Sandra Lee, 2008