Preheat oven to 350 degrees and lightly grease a 13"x9" baking dish.
Brown beef in a skillet over medium heat; drain.
Stir in tomato sauce and seasoning mix.
Bring to a boil and remove from heat.
Combine cooked macaroni, sour cream and 1/2 cup cheddar cheese in a large bowl.
Add the beef mixture to the macaroni mixture and stir to combine.
Spoon macaroni mixture into the prepared pan and sprinkle with remaining 1 cup of cheddar cheese and Parmesan cheese.
Bake, uncovered at 350 degrees for 25-30 minutes, or until hot and bubbly.
Sprinkle with chopped green onions for garnish.