Prepare the patties In a bowl, mix ground beef, breadcrumbs, egg, milk, garlic powder, onion powder, salt, and pepper. Shape into oval patties.
Brown the patties (optional but better) Sear them in a pan for 2–3 minutes per side until lightly browned.
Layer in slow cooker Add chopped onions and mushrooms at the bottom, then place patties on top.
Make the gravy In a bowl, mix beef broth and onion soup mix. Pour over the patties.
Cook Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours.
Thicken the gravy Mix flour with a little water, stir into the slow cooker, and cook for another 10–15 minutes until thickened. Add butter for extra richness.
Tips
Serve with mashed potatoes or rice for the best combo
Add a splash of Worcestershire sauce for deeper flavor
Use cornstarch instead of flour for a smoother gravy
Let it rest a few minutes before serving to thicken more
