Heat oil in a large saucepan over medium heat. Add onions and cook for 5 minutes, stirring occasionally. Add in garlic, celery, herbs, salt, pepper, and mushrooms; cook for an additional 5 minutes, until vegetables start to soften.
Mix in chickpeas, tomatoes with their juice, and broth; bring to a boil. Cover, reduce heat, and simmer for 30-45 minutes.
Stir in spinach and cook for 1 more minute, until spinach welts. Serve warm and top with Parmesan cheese (optional).