In a large skillet over medium heat, brown the ground beef while breaking it up until no longer pink, about 5-7 minutes. Drain excess fat if needed. Add the finely diced onion and sauté until it turns translucent, around 3-4 minutes.

Stir in the minced garlic and sauté for about one minute until fragrant. Pour in the tomato sauce and Worcestershire sauce, mixing well to combine all the delightful flavors.

Lower the heat and let the mixture simmer on low for about 15 minutes, stirring occasionally.

While the filling simmers, slice the garlic bread loaf in half lengthwise. Spread softened butter on each side and sprinkle with minced garlic.

Spoon the beef mixture onto the garlic bread and top with shredded mozzarella cheese. Broil on high for 3-5 minutes until cheese is bubbly and golden brown.