Broccoli-Cheese Casserole

2 (16 ounce) bags chopped broccoli
1 can cream of mushroom soup
1 can cream of chicken soup
1 cup mayonnaise
1 small can water chestnuts, sliced
12 ounces Cheddar cheese, grated

Cook broccoli according to directions on bag. Combine soups, mayonnaise and half the cheese. Layer broccoli, then soup mixture, then water chestnuts, ending with remaining grated cheese. Bake at 350 degrees F for 30 minutes.