There is something about the combination of chicken, rice, mushrooms and broccoli in a casserole that is pure comfort food.  Back in the day, we used to make the old recipe that used canned cream of mushroom soup for chicken and rice casserole.   I have yet to find a good store bought dairy free, gluten free cream of mushroom soup.  If you have the time, homemade mushroom soup in this recipe would be wonderful - just adjust liquid/rice ratio.  While this recipe does not use cream of mushroom soup, it is a yummy casserole dish for those days when comfort food is beckoning.
With this recipe, I took some guidelines from here - then made a few adjustments/additions so will do a re-cap here.
8 skinless organic chicken thighs - bone in
Season blend for chicken:
2 Tblsp. Extra Virgin Olive Oil
1 1/2 tsp. Paprika
1 1/2 tsp. Garlic Powder
3/4  tsp. Italian Seasoning
salt and fresh cracked pepper to taste
Mix ingredients in a small bowl, place chicken onto a plate and slather the season blend onto the chicken thighs rubbing in well, then put aside
1 1/2 cups basmatti rice - rinse and drain well
2  3/4 cup chicken stock
2 Tblsp. Extra Virgin Olive Oil
4-5 crimini mushrooms, diced
1 generous cup broccoli florets, cut small
1/2 a celery stalk, diced
5 minced garlic cloves
1 chopped onion
2 Tblsp. each:  fresh Italian Parsley, fresh Basil - minced
salt and pepper
grated Parmesan Cheese
Preheat the oven to 350 degrees.  Heat up a medium sized frying pan on low medium heat with a good drizzle of EVOO.  Add in the mushrooms, garlic, broccoli, celery and season with salt and pepper.  Saute 2 min. then cover with a lid - stirring a couple of times for 5 more minutes.  Remove from the heat, and add in the fresh minced Italian Parsley and Basil and mix.
Lightly oil a large square casserole/roasting pan/dish 10X13 approx. with EVOO.  Pour in the chicken stock, add in the rice stirring lightly to make even, then sprinkle in the chopped onion, and mixed vegetables.  Lay the seasoned chicken thighs on top and cover with foil.  Bake for 45 minutes.  Remove from the oven and take off the foil adding a good sprinkling of grated Parmesan Cheese through out and bake 20 more minutes.