Bring 2 quarts water to a boil in a large Dutch oven. Add linguine; cook 7 minutes or until tender. Drain in a colander; rinse under very hot water. Set aside.
Place cornstarch in bowl. Gradually add broth; stir with a whisk until blended. Add tomatoes; set aside.
Coat Dutch oven with cooking spray; add oil. Place over medium-high heat until hot. Add onion and garlic; saute 3 minutes. Add broth mixture; bring to a boil. Cook2 minutes, stirring constantly. Return linguine to pan. Stir in spinach, salt, and pepper; toss well. Spoon mixture onto plates; sprinkle with cheese and pine nuts.