Preheat the oven to 350°F and set an oven rack in the middle position. Grease a 9x13 baking dish with butter.
With a food processor, slice the potatoes into thin strips, or cut by hand. Spread a layer of the potatoes on the bottom of the pan. In a bowl, combine the cream, broth, seasonings and whisk. Put about a cup of the milk mixture over the top. Sprinkle a third of the cheese all over the layer of potatoes. Do this again two times, layering the potatoes and milk mixture and then topping with the cheese. For the top layer, end with the cheese. In a bowl, melt the butter, chopped parsley and mix the panko crumbs around until coated. Sprinkle all over the top of the potatoes and bake for 30-40 minutes, or until golden brown and bubbly.