1. Heat oil in a Dutch oven over medium-high heat. Add onion, rosemary, and garlic; sauté 3 minutes. Add mushrooms; cook 8 minutes or until vegetables are tender, stirring occasionally.
2. Stir in barley and broth. Bring to a boil; cover, reduce heat, and simmer 15 minutes or until barley is tender.
3. Add spinach, cheese, and pepper; cover and cook 2 minutes or until spinach wilts, stirring frequently.
For baby: Omit black pepper. Serve the barley mixture in a small bowl. Cut the mushrooms and spinach into bite-sized pieces, if needed.