1. Preheat oven to 400°F. Spray 13×9-inch baking dish with nonstick cooking spray.
2. Heat olive oil in large skillet over medium-high heat. Add onion; cook and stir 4 minutes or until tender. Add rice; stir to coat with oil.
3. Stir in spinach, a handful at a time, adding more as it wilts. Add broth, salt and nutmeg. Reduce heat and simmer 7 minutes. Stir in 1/4 cup cheese.
4. Transfer to prepared baking dish. Cover tightly; bake 15 minutes.
5. Remove from oven; stir in asparagus. Sprinkle with remaining 1/4 cup cheese. Cover; bake 15 minutes or until liquid is absorbed.