Few things can elevate green veggies or a pile of nachos quite like cheese that's been melted down with butter into a rich, creamy sauce, then slathered on top. Sauces, however, can be calorie-packed: A from-scratch cheese-and-butter sauce contains about 90 calories in just 2 tablespoons. Go the convenience route with processed cheese and you're looking at more than 400mg of sodium.
When we ran these numbers for our supercheesy Nachos with Pinto Bean Salsa and Pickled Jalapeños, it was obvious we needed a lighter alternative, something as rich as the cheese-and-butter sauce but almost as simple as opening a jar of processed stuff. Borrowing an idea from our Help Me, Kenji columnist, Kenji Lopez-Alt, we whisked together cheese, cornstarch, and evaporated milk over low heat until smooth. By subbing nonfat milk and using less cheese than Kenji, we created a richly dense sauce, ready in minutes, with half the calories of full-fat sauce and less salt than jarred.