Preheat the oven to 375 degrees . In a large pot of boiling, salted water, cook the pasta according to package directions until al dente. Drain, return the pasta to the pot and toss with 2 tablespoons olive oil. Cover to keep warm.
Meanwhile, on a baking sheet, toss the tomatoes with 2 tablespoons olive oil; season with salt and pepper. Roast in the oven until wrinkled, about 12 minutes.
Using a food processor, finely chop the parsley, cashews, parmesan, garlic and lemon juice. With the machine on, slowly add the remaining 1/4 cup olive oil and process until smooth; season with salt and pepper.
In a serving bowl, combine the pasta, tomatoes and pesto. Serve with more parmesan.