Slice the potatoes 1/4-inch thick.
Melt the butter in a skillet over low heat. Add the onions and saute until almost translucent. Add the garlic just before onions are done. Stir in the cream and bring to a simmer. Add the salt along with most of the Cheddar and Parmesan.
Preheat the oven to 450 degrees F.
In a baking dish make multiple layers of sliced potatoes and cream sauce ending with a layer of cream sauce. Sprinkle with the remaining Cheddar, Parmesan, and panko.
Bake the potatoes for 60 minutes. Cook's Note: Cooking time may be decreased by deep- frying the potato slices for 3 minutes and simmering the cheese sauce until the dish is ready to be assembled.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.