In a medium skillet over medium-high heat, add your ground beef, breaking it apart as it browns. Cook for 5-7 minutes until the beef is no longer pink. Add finely chopped onion and minced garlic, stirring occasionally until the onion becomes soft and translucent, about 3 minutes.

Season the beef mixture with salt and pepper to taste. Pour in Worcestershire sauce and beef broth, mixing thoroughly. Allow the mixture to simmer for 3-5 minutes on medium heat until it thickens.

Butter one side of each slice of bread. Preheat a large skillet or griddle over medium heat for about 3 minutes.

Place the buttered side of the bread down on the skillet. Add a slice of cheddar cheese, a scoop of the beef mixture, and finish with mozzarella cheese. Close the sandwich with another slice of buttered bread.

Grill the sandwiches for about 3-4 minutes on each side until golden brown and crispy, pressing down gently with a spatula.

Once both sides are golden brown and the cheese has melted, cut the sandwich in half, garnish with fresh parsley, and serve hot.