Boiling the macaroni directly in the milk saves a pot and does double duty: the starch it sheds becomes the body of the sauce, so there's no roux to whisk and no cornstarch slurry to mix. Stir often once it thickens, since that's when it wants to catch on the bottom. Dinner in under half an hour.

One-Pot Stovetop Mac and Cheese

Scale

Ingredients

2½ cups whole milk
1½ cups water
8 oz elbow macaroni
¾ tsp salt plus more to taste
2 tbsp butter
2 cups sharp cheddar, shredded off the block
1 cup Monterey Jack, shredded off the block
½ tsp dry mustard powder
1 pinch cayenne pepper

Method

Combine the milk, water, macaroni and salt in a wide skillet over medium-high heat, stirring now and then so the pasta doesn't clump on the bottom as it heats.
4 min
Once it reaches a simmer, turn the heat to medium and stir every minute or so — the starch released by the pasta wants to catch and scorch. Cook until the pasta is tender and most of the liquid has thickened into a starchy sauce clinging to the noodles.
10 min
Take the pan off the heat and stir in the butter until it melts in.
1 min
Add the cheddar and Monterey Jack a handful at a time, stirring each addition until melted before adding the next. This keeps the sauce smooth instead of greasy.
2 min
Stir in the mustard powder and cayenne, then taste and adjust salt. Serve right away — the sauce firms up fast as it cools, so loosen with a splash of warm milk if it sits.
1 min

Substitutions

Monterey Jack — All cheddar, or swap half for Gruyère if you want a nuttier, sharper sauce.
Dry mustard powder — A scant teaspoon of Dijon, stirred in with the butter.
Elbow macaroni — Any short pasta — shells or cavatappi hold the sauce especially well.

Storing leftovers

Keeps 4 days in the fridge in an airtight container. The sauce firms up as it chills, so reheat gently over low heat with a splash of milk, stirring until it loosens back into a sauce; the microwave works too, stirred every 20 seconds so it doesn't separate.

Questions

Why cook the pasta directly in the milk instead of boiling it separately?

The starch the pasta sheds as it cooks becomes part of the sauce, so there's no separate roux or slurry needed — and only one pot to wash.

Can I use pre-shredded bagged cheese?

You can, but it's coated in anti-caking starch that keeps it from melting smoothly, which can leave the sauce grainy. Shredding a block yourself melts more evenly.

What if the sauce looks broken or greasy?

That usually means the heat was too high when the cheese went in. Take the pan fully off the heat before adding cheese, and stir in a splash of milk to bring it back together.

Can I stir in mix-ins like broccoli or bacon?

Yes — fold in steamed broccoli florets or cooked, crumbled bacon at the very end, after the cheese has melted in.