In a bowl, gently mix ground beef, breadcrumbs, egg, milk, onion powder, garlic powder, Worcestershire sauce, salt, and black pepper. Try not to overmix.

Shape the mixture into 5 to 6 oval patties, pressing a slight dip in the center for even cooking.

Heat oil or butter in a large skillet over medium-high heat and brown the patties for about 3 to 4 minutes on each side, then transfer them to a plate.

In the same skillet, add mushrooms and onions, allowing them to brown while stirring occasionally.

Pour in beef broth, scrape up the browned bits, then add ketchup and Worcestershire sauce. Bring to a gentle simmer.

Slowly stir in the flour slurry while simmering until the gravy thickens, adding broth or water if it becomes too thick.

Return the patties to the gravy, spooning sauce over each one. Cover and simmer for 8 to 12 minutes until cooked through.

Taste the gravy at the end and adjust seasoning with salt and pepper as needed.