Plug in the slow cooker and set it to low heat. Spray the insert with non-stick cooking spray or coat it with olive oil.

In a large mixing bowl, combine ground beef with breadcrumbs, egg, garlic powder, onion powder, salt, and pepper. Mix gently and form into oval patties.

In a large skillet over medium-high heat, add olive oil and sear the patties for 3-4 minutes per side. Transfer to the slow cooker.

In the same skillet, add sliced onions and cook for about 5 minutes. Stir in flour, then gradually add beef broth, garlic, and Worcestershire sauce, whisking to avoid lumps. Cook until thickened.

Pour the gravy over the patties in the slow cooker and sprinkle Italian seasoning over it.

Cover and cook on low for 6-7 hours.

Check for doneness and if necessary, thicken gravy with cornstarch and water.

Serve the patties topped with gravy alongside mashed potatoes or steamed vegetables.