Preheat oven to 350 degrees. In a small bowl, mix the 6 tablespoons melted butter, El Greco, salt and pepper. Coat a non-stick 8-inch skillet, or a well-seasoned cast iron pan, with butter.
Using a mandoline, thinly slice the potatoes into circles to almost paper thin. Arrange the potato slices in an overlapping circle at the bottom of the skillet, working quickly so that the potatoes don't oxidize.
Brush each layer with the butter and seasoning mixture. Keep repeating until all the potatoes have been added to the pan, and the butter and seasoning mixture is used.
Cover the potatoes with a lid and set on medium-high heat on the stove top for 4-5 minutes. You want the edges to barely start to get color and pull away.
Put the pan with the pommes in the oven and bake for 30-40 minutes, or until the center of the dish is easy to pierce through with a knife.
Remove potatoes from the oven and let rest for 3 minutes. The potatoes should naturally pull away from the edges of the pan, but to guarantee an easy release, run a spatula along the edges of the pan.
Next, put a plate larger than the pan on top of the pommes. Using a towel to protect you from the heat, flip the pan over quickly onto the plate.
Cut into wedges and serve warm.