For the onions
01 -
2 tablespoons unsalted butter
02 -
2 large yellow onions, thinly sliced
03 -
1/4 teaspoon kosher salt
For the meatloaf
04 -
2 lb (900 g) ground beef, preferably 85/15
05 -
1 cup (60 g) panko breadcrumbs
06 -
2 large eggs, lightly beaten
07 -
1/2 cup (120 ml) whole milk
08 -
1 packet (1 oz/28 g) dry onion soup mix
09 -
1 tablespoon Worcestershire sauce
10 -
1 teaspoon Dijon mustard
11 -
1/2 teaspoon dried thyme
12 -
1/2 teaspoon black pepper
For the gravy and topping
13 -
1 cup (240 ml) low-sodium beef broth
14 -
1 tablespoon Worcestershire sauce
15 -
1 tablespoon cornstarch mixed with 1 tablespoon cold water, optional
16 -
6 slices Swiss cheese or 1 1/2 cups shredded Gruyere
17 -
1 tablespoon chopped fresh parsley, optional