Combine chicken stock and rice together in a saucepan. Bring to a boil, and cover. Reduce heat to low and simmer for 20 minutes until all liquid is observed.
Preheat oven to 350 degrees, and grease a 9x13 baking pan. While rice is cooking, slice meatballs, half mushrooms, dice tomatoes and shred cheese.
Combine cooked rice, meatballs, mushrooms, tomatoes, olives, cumin, chipotle and cheese together. Spread mixture out onto the baking dish. Bake for 15 minutes or until heat through. Top with chopped cilantro and serve.
Cooking 2 cups of rice takes about the same time as cooking 4 cups. Schedule Chicken Broccoli & Rice Casserole in the same week as this and save yourself a little cooking time!