Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add thinly sliced onions and sauté for about 10-12 minutes until caramelized.

Stir in 2 minced garlic cloves and cook for an additional 1-2 minutes until fragrant.

Add 1 pound of lean ground beef, breaking it apart. Cook for 5-7 minutes until browned.

Drain excess fat, then stir in 1 tablespoon of Worcestershire sauce, 1 tablespoon of soy sauce, salt, pepper, and 1 teaspoon of fresh thyme. Simmer for 5 minutes.

While simmering, preheat oven to 350°F. Toast hamburger buns on a baking sheet for 5-7 minutes until golden.

Scoop a portion of the beef mixture onto each bun, top with Swiss cheese, and let it melt slightly.

Place the top bun over each sandwich and sprinkle with chopped parsley if desired. Serve warm.