Step 1: Prep your space and oven. Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with non-stick spray or butter.
Step 2: Brown the meat. Place a large skillet over medium-high heat. Add the beef and diced onion. Cook for 5-7 minutes until the meat is browned and no pink remains. Drain any excess grease.
Step 3: Add the aromatics. Stir the minced garlic into the skillet. Cook for exactly 1 minute until highly fragrant. Remove the skillet from the heat.
Step 4: Mix the savory sauce. In a medium bowl, whisk the cream of mushroom soup, milk, Worcestershire sauce, salt, and pepper. Stir until smooth and creamy.
Step 5: Assemble the layers. Spread half of the sliced potatoes evenly in the prepared baking dish. Top with the cooked beef mixture. Pour half of the creamy sauce over the meat. Add the remaining potatoes, then cover with the rest of the sauce.
Step 6: Bake covered. Cover the dish tightly with aluminum foil. Bake for 35 minutes. The foil traps steam, ensuring the potatoes become perfectly tender.
Step 7: Melt the cheese. Remove the foil carefully to avoid hot steam. Sprinkle the grated cheddar cheese evenly over the top. Return the dish to the oven, uncovered.
Step 8: Final bake. Bake for 10-15 more minutes. Watch for bubbling edges and a golden, melted cheese crust. Let it rest for 5 minutes, garnish with parsley, and serve.
