MAPLE-DIJON ONION TOPPING
2 tablespoons butter
1 tablespoon olive oil
3 medium-large onions, thinly sliced
Salt and pepper
Water or chicken stock
1/3 cup dark amber maple syrup
1/4 cup grainy Dijon mustard
2 pounds ground beef chuck
3 to 4 tablespoons Worcestershire sauce (I use Lady Jayne, but I also love Lea & Perrins)
2 rounded tablespoons prepared horseradish (I like Gold’s)
A handful of flat-leaf parsley, finely chopped
Kosher salt and pepper
All-natural cooking spray
4 hamburger rolls, split and toasted (we used Amy’s)
8 slices bacon (see note)
8 slices sharp Cheddar cheese (I use XXX from Oscar’s Smokehouse)
Watercress, for serving
Make the maple-Dijon onion topping: In a large skillet, melt the butter in the olive oil over medium heat. Add the onions and season with salt and pepper. Let them caramelize for 25 to 30 minutes, stirring frequently. You can add a splash of water or chicken stock to the onions if they get too dry. Stir in the maple syrup and mustard.
Make the burgers: In a large bowl, combine the meat, Worcestershire, horseradish, and parsley; season with salt and pepper. Score the mixture into 4 equal portions and form them into patties, making them thinner at the center and thicker at the edges for even cooking and presentation.
Coat a cast-iron skillet or griddle with cooking spray. Cook the burgers until your desired doneness. Serve the burgers on the hamburger rolls and topped with the bacon, cheddar, maple-Dijon onions, and watercress. Absolutely delicious.