Preheat the oven to 400 degrees.
Add the ground beef to a skillet and brown the meat, chopping as it cooks. Then drain the grease.
Fill a medium saucepan half full with water. Bring to a boil.
Pour the noodles from the box of macaroni and cheese in and cook for 5 minutes, or until noodles are tender, but not quite done.
Pour noodles into a strainer to drain the water, then return to the saucepan.
Add butter, cheese packet from box of mac and cheese, and milk, stir well.
Add mixed veggies, cream of mushroom soup, and ground beef to a large bowl and mix. Pour into a large casserole dish.
Top the mixture evenly with the macaroni and cheese.
Bake for 25 minutes.
Remove from the oven and serve hot!