Brown meat, onions, salt, pepper, garlic and mushrooms, drain if needed, set aside.
Boil macaroni, drain set aside.
In a large oven safe bowl (pyrex) combine ALL above ingredients, mix thoroughly. Cover with aluminum foil, back 30-40 minutes Take the dish out of oven, remove cover, stir once, put the dish back in the oven uncovered for 5-10 minuted to create a goldnish crust on top. Let stand for at least 15 minutes.