Place a plastic colander over a bowl or baking dish. Crumble meat in colander. Add onion and microwave at full power for 6 minutes, stirring once during cooking. Remove from microwave and crumble. Place hamburger and onions in a large casserole that has been sprayed with Pam. Add remaining ingredients including dry macaroni.
Cover and cook on full power for 10 minutes, stirring twice during cooking.
