Shape the ground beef into 4–6 oval patties, pressing them a little thinner in the center so they cook evenly.
In a medium bowl, whisk together the condensed cream of mushroom soup, brown gravy mix, and water until smooth and well combined.
Lightly spray the slow cooker with nonstick cooking spray.
Spoon a thin layer of the gravy mixture onto the bottom of the slow cooker.
Arrange the beef patties in a single layer (it’s okay if they overlap a bit).
Pour the remaining gravy mixture evenly over the patties, making sure they’re mostly covered.
Cover and cook on LOW for 5–6 hours, or on HIGH for 2 ½–3 hours, until the patties are cooked through and tender.
Taste the gravy and adjust seasoning with a little salt and pepper if needed.
Serve the Salisbury steaks hot, spooning plenty of gravy over each patty.
