Ingredients:

– 1 lb ground beef (80/20 blend)
– 1 teaspoon salt
– 1/2 teaspoon black pepper
– 1 tablespoon Worcestershire sauce
– 4 slices Swiss cheese
– 1 large onion, thinly sliced
– 2 tablespoons butter
– 1 tablespoon olive oil
– 2 cups beef broth
– 1 teaspoon fresh thyme leaves (or 1/2 teaspoon dried thyme)
– 4 burger buns
– Fresh parsley, chopped (for garnish)

Instructions:

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