Preheat the oven grill to 220°C. In a large saucepan, heat the olive oil and add the chicken. Stir occasionally until it turns golden on all sides. Add the onion and cook for 5 more minutes over medium heat. Add the garlic, herbs and orzo. Add the boiling water and bouillon cube. Simmer for 15 minutes on low heat until water has been absorbed and orzo is cooked. Add the spinach and cook for a while until wilted. Turn off the heat to let it cool for a few minutes and then add the yogurt and cheddar cheese, mixing thoroughly until the cheese has melted.
Transfer to a baking dish and sprinkle with the bread crumps on top. Place on the top rack of the oven and cook for 5-7 minutes until toasted on top.