Buttered-Toast Swiss Patty Burger

In 'The Book of Burger' by Rachael Ray

• Ready In: 40 mins
• Serves: 4

Ingredients

• 3  tablespoons butter (2 of them soft)
• 1  large onion, chopped
•  ground thyme, 2 pinches
•  kosher salt
•  pepper
• 1 1⁄2 lbs  ground chuck
• 1  tablespoon Worcestershire sauce
• 1 1⁄2 teaspoons  extra-virgin olive oil
• 4  thin slices swiss cheese
• 8  slices  sandwich bread
• 1  tablespoon Dijon mustard
•  chicken stock or  water
• 1  tablespoon  finely chopped flat leaf parsley

Directions

1. Melt 1 tablespoon butter in a medium skillet over med-low heat.
2. Add the onion and thyme, season with salt and pepper, and cook until the onion is lightly browned, about 15 minutes.
3. While the onion is cooking, combine the beef and Worcestershire sauce in a large bowl; season with salt and pepper and mix thoroughly.
4. Score the mixture into 4 equal portions and form them into patties slightly thinner at the center than at the edges for even cooking and to ensure a flat surface.
5. Heat the oil in a large nonstick skillet over med-high heat until very hot.
6. Cook the burgers, turning once, 10 minutes for medium.
7. Top the burgers with the cheese for the last minute of cooking, tenting the skillet with foil, if you like, to help the cheese melt.
8. While the burgers are cooking, toast the bread, then spread with the remaining 2 tablespoons softened butter.
9. Stir the mustard and a splash of chicken stock into the onions.
10. Stir in the parsley, then remove from the heat.
11. Place a burger on each of 4 buttered toasts and top with some onions.
12. Set the remaining buttered toast on top.