Heat oil in large saucepan over medium-high heat. Add mushrooms, basil, garlic and pepper; cook and stir 5 minutes or until mushrooms are tender.
Add rice and salt; cook and stir 2 to 3 minutes or until rice is translucent. Add wine; cook and stir until absorbed. Add broth. 1/2 cup at a time, stirring until broth is absorbed before adding next addition. Add spinach with last 1/2 cup broth is absorbed.
Cover and let stand 5 to 7 minutes or until spinach is wilted. Sprinkle with walnuts and cheese before serving.
Notes
*To toast walnuts, spread in single layer in heavy skillet. Cook over medium heat 2 to 3 minutes or until lightly browned, stirring frequently.