Heat 2 teaspoons oil in a large skillet over medium-high heat. Add zucchini to pan; sauté 5 minutes or until tender and golden. Remove from pan; cool.
Place 1/4 cup cooked zucchini, basil, 1/4 cup cheese, pine nuts, and garlic in a food processor; process until finely chopped. (Keep mixture in processor.)
Heat remaining 2 teaspoons oil in a large skillet over medium-high heat. Add onion to pan; sauté 10 minutes or until golden. Return remaining cooked zucchini to pan. Remove from heat.
Combine 6 quarts water and 1 teaspoon kosher salt in a large Dutch oven, and bring to a boil. Cook pasta in boiling water according to package directions. Drain in a sieve over a bowl, reserving 1/3 cup cooking liquid. Add pasta to vegetables.
With processor on, add reserved liquid to basil mixture; process until smooth. Add basil mixture to pasta. Add cream, remaining salt, and pepper; stir. Top with remaining cheese.