Once done, taste the gravy and adjust with a pinch of salt and black pepper if needed. Serve the hot patties straight from the slow cooker, spooning plenty of the rich brown gravy over each portion so those golden-brown edges peek through under the sauce.
If you like a bit more texture, mix 1/4 cup plain dry breadcrumbs into the meat along with the onion soup mix to help the patties hold together, especially if you’re using leaner beef. You can swap cream of mushroom soup for cream of chicken or cream of celery if that’s what’s in your pantry; the flavor will change slightly, but the meal will still be hearty and comforting. For a deeper, almost pot-roast-like flavor, replace the water with beef broth. If your gravy is thinner than you like at the end of cooking, crack the lid and let it simmer on HIGH for 15–20 minutes, or stir in a slurry of 1 tablespoon cornstarch mixed with 1 tablespoon cold water and cook until thickened. To stretch the meal for extra mouths, add a layer of thickly sliced onions or mushrooms under the patties before pouring on the soup mixture. Leftovers reheat beautifully; the patties get even more tender overnight, so don’t be afraid to make the full batch even if you’re only feeding two people.