In a large mixing bowl, combine ground beef, breadcrumbs, finely chopped onion, milk, egg, Worcestershire sauce, garlic powder, salt, and pepper. Gently mix with your hands until just combined.

Shape the mixture into 4-6 oval patties, approximately ¾ inch thick, then set them aside.

Heat a tablespoon of olive oil in a large skillet over medium-high heat. Once shimmering, place the patties in the skillet without overcrowding. Sear each side for 4-5 minutes until browned.

Remove the patties and set aside, leaving the juices in the skillet.

In the same skillet, reduce heat and add 2 tablespoons of unsalted butter. Once melted, add sliced mushrooms, onion, and minced garlic, sauté for about 5 minutes until softened.

Sprinkle in flour and stir for about 1 minute. Gradually whisk in beef broth and additional Worcestershire sauce; bring to a gentle boil.

Reduce heat and simmer for 5-7 minutes until thickened. Season with salt and pepper.

Return the patties to the skillet, spoon gravy over them, cover, and simmer gently for 3-4 minutes.

Garnish with fresh parsley and serve alongside mashed potatoes or egg noodles.