Macaroni and Cheese (boxed)

The box assumes you have milk and butter. You don't need both. You don't even need either one.

How to make it

Boil about 6 cups of water in a pot.
Add the macaroni and stir. Boil for 7 to 8 minutes, until soft.
Use a mug to scoop out ½ cup of the cooking water before you drain. You may need it.
Drain the pasta and put it back in the pot.
Add the cheese powder and your liquid and fat (see the tips below). Stir until creamy.

No milk? Use about ¼ cup of the pasta water you saved. Shelf-stable milk (the boxed kind that doesn't need the fridge until you open it) works too. For powdered milk, stir about 1 tablespoon of powder into ¼ cup of water.
No butter? Use a tablespoon of oil, or just leave it out and add a bit more pasta water.
No milk and no butter? Pasta water alone works. The sauce will be a little thinner, and it will still taste good.
A spoon of sour cream makes it extra creamy if you have some.
Lumpy cheese powder? Stir it into the milk or pasta water first, then pour that over the pasta.
One box feeds 2 or 3 people. Add a can of tuna, some peas, or sliced hot dogs to make it a real meal. See Upgraded Mac and Cheese.

Unopened boxes keep a long time. A box a little past its date is usually fine, but the cheese may taste a bit flat.
Leftovers keep 3 to 5 days in the fridge. Add a splash of water or milk when you reheat.