Mexican Chicken Casserole

3 chicken breast cooked and de-boned (I use the chicken out of a can but you don't have to)
1 can cream of chicken soup
1 can cream of mushroom soup
1 can Rotel tomatoes
1 can chicken broth
1 small onion (chopped)
8 oz grated sharp Cheddar cheese
1 Tbsp butter
Tortilla chips
.

Saute the onions in butter. Add the soups, broth and the tomatoes. Simmer for about 5 minutes. Meanwhile layer a casserole dish with the tortilla chips, then half the chicken, half the cheese and then half the sauce. Then repeat with the remaining ingredients. Bake at 350 degrees for 35 minutes.