Position knife blade in a food processor bowl, add the first 4 ingredients. Process until smooth, stopping once to scrape down sides. Pour the olive oil through the food chute with the processor running, process until smooth. Set pesto mixture aside. Place the pasta in a large bowl. Add 1 1/2 cups of pesto mixture and artichoke hearts. Reserve the remaining pesto mixture for another use. Sprinkle the pasta with tomatoes and serve hot or cold. Makes 8 servings