1. Preheat your oven to 375°F (190°C). Grease a 9×13-inch baking dish and set it aside.
2. In a large skillet over medium heat, cook the Italian sausage until browned and crumbled. Remove and drain off any excess fat.
3. In the same skillet, add the onion and cook until translucent, then add the garlic and cook for another minute. Remove from heat.
4. In a large bowl, combine the sausage, cooked onion and garlic, shredded cheddar cheese, sour cream, cream of mushroom soup, milk, salt, and black pepper. Mix well.
5. Layer half of the sliced potatoes in the prepared baking dish. Spread half of the sausage mixture over the potatoes. Repeat with the remaining potatoes and sausage mixture.
6. Drizzle the melted butter over the top of the casserole.
7. Cover the baking dish with foil and bake in the preheated oven for 45 minutes. Then remove the foil and bake for an additional 15 minutes, or until the potatoes are tender and the top is golden and bubbly.
8. Allow the casserole to cool for a few minutes, then sprinkle with chopped fresh parsley if desired before serving.
Variations & Tips
For a lighter version, you can use turkey sausage and substitute Greek yogurt for sour cream. If you have picky eaters, consider using mild cheddar cheese or even mozzarella for a less sharp flavor. You can also add in some frozen peas or corn for added vegetables. For those who enjoy a little spice, toss in some red pepper flakes or use spicy Italian sausage.
