Preheat your oven to 375 degrees Fahrenheit. Lightly grease a large 9x13-inch baking dish and set aside.
Heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook for 2-3 minutes until soft. Add the minced garlic and ground beef, breaking up the meat as it cooks, until browned. Stir in the salt and black pepper.
In a mixing bowl, combine the condensed cream of mushroom soup, milk, and Worcestershire sauce. Whisk until fully blended.
Layer half of the sliced potatoes in the prepared baking dish. Spoon half of the beef mixture over the potatoes, then pour half of the sauce and sprinkle half the cheese on top. Repeat the layers.
Cover the dish tightly with foil and bake for 50-55 minutes. Remove the foil and bake another 10-15 minutes, until the potatoes are tender and the cheese is bubbly.
Let the casserole rest for 10 minutes before serving. This helps the layers set for easier slicing. Serve hot and enjoy!
