- Cut the peeled potatoes into 1/8-inch thick slices.
- Preheat oven to 450 degrees.
- In a small bowl, combine the salt, pepper, zest and thyme. Swirl just 2 tablespoons of butter in a 10-inch cast-iron or ovenproof heavy skillet over medium heat.
- Arrange a single layer of potato slices, slightly overlapping, in a circular pattern in the pan; sprinkle with 1/4 of the herb mixture. Use a pastry brush and lightly brush 1/2 teaspoon of the melted butter over potatoes.
- Repeat layers 5 times, ending with butter, herb mixture.
- Press firmly to pack.
- Cover and bake 450 degrees for 20 minutes.
- Uncover and bake an additional 25 minutes or until potatoes are golden.
- Serve the potatoes in the skillet or loosen edges with a spatula and turn over onto a plate. Sprinkle with parsley.