Preheat your oven to 375°F (190°C).

In a large skillet over medium heat, brown the smoked sausage slices until fully cooked. Set them aside.

Using the same skillet, sauté the diced onion and minced garlic until they become translucent.

In a large mixing bowl, combine the diced potatoes, cooked sausage, sautéed onion and garlic, shredded cheddar cheese, ranch dressing mix, milk, and melted butter. Season with salt and pepper to your liking.

Transfer this mixture into a greased baking dish, spreading it out evenly.

Cover the dish with aluminum foil and bake in the preheated oven for 60 minutes. Afterward, remove the foil and bake for an additional 15 minutes, or until the potatoes are tender and the top is golden brown.

Garnish with chopped green onions before serving. Enjoy the delicious and hearty meal!.