Combine the pasta, water and salt in a large microwave-safe mug.

Set it on a paper towel and microwave on high in 2-minute intervals, stirring in between, until the pasta is just short of tender (al dente. This should take 4 to 8 minutes, depending on the wattage of your microwave. (The water will foam up and possibly spill slightly over the mug, but the pasta and mushrooms should stay put.) If the mug dries out before the pasta is cooked, add another 2 tablespoons of water before continuing to microwave until the pasta is al dente.

Stir in the milk, cheese, and flour. Microwave on high in 30-second intervals, stirring in between, until the cheese has melted and a creamy sauce has formed. Let cool slightly and eat.

For something more basic, leave out the mushrooms. You can also take it in the other direction and add all sorts of other ingredients, depending on what's in your office fridge: pesto, leftover meat, Sriracha, kimchi. .