You will also need a well seasoned 9-inch non-stick or cast iron skillet, kitchen Mitts, a spatula and a hot oven.
You have already selected some nice uniform potatoes for this dish. They will need to be sliced carefully into ¼ inch slices. If you have access to a mandolin, this would be a great time to use it.
Hold the potatoes in cold water until time to assemble the casserole. They will need to be dried before assembly.
When done, this potato dish will be inverted (served with the bottom facing up) for service and presentation, so we will carefully select the most uniform pieces for the first layer.
About the butter, we will only be using the clear (clarified) part of the butter. You can go through the process of clarifying your butter or you can just slowly melt the butter and skim off and use the clear part, leaving the milky solids in the bottom of your pan.
Preheat your oven to 450° F.
To begin, heat the pan on the stove until it is warm and ladle in an ounce or so of the butter.
Using the most uniform potato slices, begin the circles in the center of the pan, slightly overlapping each slice.
Once a circle is complete, repeat but reverse direction of each circle until the surface of the pan is covered, about four circles depending on the diameter of your potatoes.
Season the first layer of potatoes with salt and pepper and either brush the top of the layer with or ladle some more butter on the potatoes.
Repeat the process until done, about four layers or so of potatoes. There will appear to be too much butter for your liking. Don’t worry, you will drain that off before service and it can be used again.
Put the pan on the stove over medium heat for 4 or so minutes until you hear the pan sizzling. Shake the pan slightly a time or two to make sure the potatoes are not sticking.
Cover the pan with foil and put into the preheated oven for about 40-45 minutes, or until the potatoes are fork tended in the center. Remove the foil and cook for an additional 10 minutes uncovered.
Prepare a heatproof receptacle for the hot butter, maybe a clean tin can or glass dish. Holding the pan in one hand and holding the potatoes in place with a flat spatula, carefully tilt the pan over the receptacle and drain off the butter.
Now you will need a serving plate for presentation or a cutting board if you intend to cut into portions and serve at once.
Loosen the edges of the potatoes if necessary with a spatula if necessary, then hold the plate or cutting board over the skillet and quickly invert it, being conscious of the possibility of hot butter running out. (I always do this over a sink wearing Kitchen Mitts).
If a potato or two sticks to your pan, remove it with the spatula and place it on the mound of potatoes.
To serve portions, cut into wedges like a pizza and garnish with a little chopped parsley.