Fry the meat and onion in a large skillet. Meanwhile cook the macaroni in a large pot. Drain the macaroni and return it to the pot. When the meat is cooked, drain off any fat and add it to the big pot of drained macaroni. Next, open up all three cans and dump their contents into the pot. Add the salt and garlic powder. Stir everything up real good. Heat through and serve with cheese sprinkled on top. Or, if you can wait, then turn the goulash into a 9-13-inch pan or a 2 quart casserole dish that has been sprayed with cooking spray. Sprinkle the cheese on top. This may now be baked or refrigerated or frozen. If you are cooking it immediately then bake at 400 for 20 minutes. If it's cold from the frige cook it for 35 minutes. If it is frozen, cook at 350 for at least an hour, with the top covered with tin foil.