In a large deep skillet place our cream cheese soup and sour cream and cook on med low until melted and smooth. Pour in milk and garlic salt
Place the potatoes in a large bowl. Toss in the onions and garlic. Pour the cream mixture over the potatoes and stir to coat. Stir in 1 cup of cheese and stir.
Pour into a buttered casserole dish 11x13 top pour melted butter over top and poke holes for butter to go down through.. I even top with additional garlic but this is totally depends on how much you like garlic.
Bake 375 for about 40 mins covered then remove the last 5 mins and top with the last cup of cheese.