Preheat oven at 350 degrees F. Brown ground beef, onions and chilies in saucepan. Add tomatoes, cheese soup and mushroom soup and stir. Add 1 1/2 cups shredded cheese and stir until melted. Crunch Doritos slightly, add to beef mixture and stir well.
Pour into casserole dish and sprinkle with remaining cheese.
Place in oven and bake until cheese is melted on top (about 15 minutes). Remove from oven and serve.