Preheat & Prep: Preheat your oven to 350°F. Grease a 9x13-inch baking dish and set aside.

Cook the Meat: Place the ground beef and chopped onion into a skillet over medium-high heat. Cook until the meat is fully browned and the onions have softened. Drain any excess grease.

Make the Sauce: In a separate mixing bowl, whisk together the Cream of Mushroom soup, heavy whipping cream, beef broth, dried rosemary, garlic powder, and a generous pinch of salt and pepper.

First Layers: Place half of the sliced potatoes in an even layer at the bottom of the prepared baking dish. Spread ⅓ of the creamy soup mixture over the potatoes, followed by ½ of the cooked meat mixture.

Second Layers: Add the remaining potatoes in an even layer. Top with another ⅓ of the soup mixture, and then the rest of the meat mixture.

Top & Bake: Pour the very last of the soup mixture over the top. Sprinkle evenly with the shredded cheese.

Bake: Cover the baking dish tightly with aluminum foil. Bake for 1 hour and 30 minutes, or until the potatoes are completely tender when pierced with a fork.

Rest & Serve: Remove from the oven and let the casserole rest for 10 minutes before slicing. Enjoy!