Heat a large skillet over medium heat. Add the lean ground beef and cook until fully browned, breaking it into small crumbles as it cooks. Drain excess grease.

Stir in the diced onion and minced garlic. Cook for about 5 minutes until onions are tender and lightly golden.

Sprinkle the flour evenly over the meat and onion mixture. Stir well to coat everything and cook for 2 minutes to remove the raw flour taste.

Slowly pour in the beef broth while stirring constantly to avoid lumps. Continue stirring until the mixture begins to thicken and reaches a gentle simmer.

Add Worcestershire sauce, salt, and pepper. Let the gravy simmer for another 5 minutes until rich and smooth. Adjust thickness by adding more broth if needed.

Place mashed potatoes on serving plates and spoon the hot gravy generously over the top. Serve immediately.