Bring the barley and chicken broth to a boil in a saucepan over high heat. Cover, reduce heat to low, and simmer until the barley is tender, about 30 minutes.
Heat the olive oil in a skillet over medium heat. Stir in the celery, carrots, garlic, and onion; cook and stir until the onion has softened and turned translucent, about 5 minutes. Stir in the mushrooms, zucchini, green beans, and broccoli. Continue cooking and stirring until the broccoli is tender, about 5 minutes more. Remove skillet from heat.
Combine cream cheese, cream of chicken soup, sour cream, Locatella cheese, Parmesan cheese, garlic powder, nutmeg, oregano, basil, and thyme in a large bowl, mixing until smooth. Stir in the prepared barley, peas, corn, roasted red peppers, spinach, and shredded chicken. Season with salt and pepper. Spread mixture into a large baking dish and top with mozzarella cheese.
Bake in the preheated oven until bubbly, and cheese has melted, 20 to 30 minutes.
