Chicken and rice casserole

Josh really loved this one.  I have to post it.  It was simple and delish.

3 Tbs. olive oil
1 onion, diced
3 stalks celery, diced
3 carrots, peeled and diced
2 Tbs. fresh minced garlic
2 cups shredded, cooked chicken
3 cups (already cooked) white rice
1 tsp. salt
1/2 tsp. pepper
1/4 tsp. garlic salt

Cheese sauce:
4 Tbs. butter
1/4 cup flour
1/4 tsp. salt
1/4 tsp. pepper
2 cups chicken broth
2 cups shredded cheddar cheese

*Heat oil in a skillet on stove.  Saute onion, celery, and carrots for about 10 minutes.  Add garlic and cook for 1 more minute.  Stir in chicken, rice, salt, pepper and garlic salt.  Reduce heat to low.  Prepare cheese sauce by melting butter in a saucepan over medium heat.  Whisk in flour, salt, pepper and chicken broth.  Whisk continuously until thick and nearly bubbling.  Stir in cheese until melted.  Put rice mixture in a casserole dish and pour cheese sauce over it.  Stir to combine.  You can sprinkle some more cheese on top.  Bake for 30 minutes on 350.  My friend found this recipe on picky-palate.com