Pasjoli’s Croque Matthieu

This buttery, toasty, crispy, melty grilled cheese sandwich — it might be the best grilled cheese you ever make — features layers of nutty Gruyère, caramelized onions, thinly sliced cured ham and creamy Mornay sauce (a béchamel studded with cheese).

The onions are slowly, slowly caramelized and can take up to several hours, stirring every 15 minutes, to attain their deepest flavor. At his restaurant Pasjoli, chef Dave Beran says the pot of onions is started in the morning and anyone who walks by it during the day gives it a stir. You probably don’t have a team of chefs in your kitchen, but the good news is you can get a lot of flavor in a couple of hours. The key is not to let them cook too quickly so that the onions develop their own flavor and color fully over time. Plus, you’ll have leftovers for using in just about anything — soups, stews, with roasts or more sandwiches.

Named after former Pasjoli chef de cuisine Matthew Kim, Dave Beran melts the Gruyère in a pan to create a crust on the surface of the bread that serves as a crackly cheesy layer.

The recipe for Mornay sauce also makes more than you need for the sandwiches. Both the caramelized onions and Mornay freeze well.