1 lb Italian sausage, casing removed
6 medium potatoes, peeled and thinly sliced
1 medium onion, diced
2 cloves garlic, minced
2 cups shredded cheddar cheese
1 cup sour cream
1 can (10.5 oz) cream of mushroom soup
1/2 cup milk
1 teaspoon salt
1/2 teaspoon black pepper
2 tablespoons butter, melted
1/4 cup chopped fresh parsley (optional for garnish)