Mexican Chicken Casserole

I got this recipe from one of Tim's co-workers, and it's been a family favorite for us.

In a 9 x 13 dish, layer:

3 cups cooked, chopped chicken breasts
1 onion, chopped
1 lb. of Velveeta, grated or cubed (if using the block Velveeta)
1 8 ounce bag of Doritos (I get an 11 oz. bag and don't quite use it all)--I break the chips up a bit, not quite crushed--and sprinkle them over the top of the other layers.

In a bowl, combine:
1 can Rotel
1 can cream of mushroom soup (I use fat free)
1 can cream of chicken soup (I use fat free)
1 cup of chicken broth

Pour mixture all over the top of the casserole.

Bake at 350 degrees for 30-40 minutes, until it's good and bubbly.