Preheat oven to 350 degrees.
Start by spraying your baking dish with non-stick cooking spray.
Peel the potatoes if desired. Slice the potatoes. You will want the potatoes a thin 1/8"-1/4", as evenly as possible.
In a medium mixing bowl, combine the chicken broth (vegetable broth can easily be substituted for the chicken broth), sour cream, half of the cheddar, parmesan cheese, garlic salt, onion powder, fresh, thyme and the pepper.
Spread half of the sliced potatoes in the bottom of your greased baking dish. Pour half of the sauce over the potatoes. Spread the remain potatoes in the baking dish and add the rest of the sauce and the rest of the cheese.
Cover loosly with alluminum foil and Bake in a 350-degree oven for about 1 hour or until the edges and top of the scalloped potatoes are golden brown. The potatoes should be soft when poked with a fork. Take the foil off and continue to cook for 15-20 minutes until the cheese on top becomes golden brown.
Take the baking dish out of the oven and let these delicious homemade scalloped potatoes cool for about 5 minutes before serving. Enjoy!