Grease a larger-size casserole dish (enough to hold the mixture, I use my white Corning Ware 13 x 9-inch baking dish for this).
Place the sliced potatoes in the the baking dish.
In another bowl, combine the soup, sour cream, cubed Velveeta cheese, whipping cream, melted butter, seasoning salt, (I use about 1 teaspoon) and pepper to taste minced garlic, chopped onion and 1/3 cup Parmesan cheese; mix well to combine.
Pour over the potatoes in the dish; mix/toss to coat.
Top with remaining 1/3 cup (or to taste) grated Parmesan cheese.
Bake, covered for about 1 hour and 15 minutes, or until potatoes are tender, (uncover for the last 15 minutes of baking).
NOTE about 15 minutes before removing from oven, if desired sprinkle about 1 cup of grated cheddar cheese on top, then return to oven for about 15 minutes, this is optional only.