Prep the Slow Cooker: Lightly grease the inside of a 4- to 6-quart slow cooker with nonstick cooking spray or a thin film of cooking oil to help prevent sticking.

Season the Meat: In a medium-sized mixing bowl, sprinkle the ground beef with the black pepper. Gently mix with your hands just until the pepper is evenly distributed, being very careful not to overwork the meat.

Form the Patties: Divide the seasoned ground beef into 4 equal portions. Shape each portion into a flat, even oval or round patty, approximately ½ to ¾ inch thick.

Layer the Beef: Lay the raw hamburger patties in a single, even layer on the bottom of your prepared slow cooker. It is fine if the edges touch slightly, but do not stack them.

Mix the Gravy: In a separate medium bowl, vigorously whisk together the condensed cream of mushroom soup, dry onion soup mix, and water until the mixture is mostly smooth and well combined.

Pour and Cover: Pour the thick cream of mushroom soup mixture evenly over the raw hamburger patties in the slow cooker, making sure every single patty is fully covered.

Cook to Perfection: Secure the slow cooker lid. Cook on the LOW setting for 5 to 6 hours, or on the HIGH setting for 2 ½ to 3 hours, until the patties are completely cooked through (no pink remaining in the center) and perfectly tender.

Serve: Taste the rich brown gravy and adjust the seasoning with a pinch more pepper if needed. Serve the hot patties immediately, spooning plenty of the mushroom-onion gravy over the top alongside mashed potatoes or egg noodles.