I use to go with
2 box generic macaori n cheeze
1 can campbell's Cheese soup
1 cup sharp cheddar cubes
1 cup milk
cook up the macarroni and add in the powder cheeze and mix. keeping the pot on a low heat add in cubes and soup and mix till cubes have melted. then add milk to make as gooey or soupy as desired.
Hope it works out for you, but Cambell's cheeze soup has changed over the years so now I use Rago's cheese sauce.