Pie plate (glass preferred)
Mandoline (not necessary but useful)
Unpeeled, well-scrubbed russet or other baking potato, in thin slices (use mandoline here)
Sliced white button or other mushrooms (cremini would be good, too)
Onion cut in thin slices, slices separated into strands
Grated parmesan or diced mozzarella cheese (smoked would be great!)
Salt and pepper (white if available)
Heat oven to 350 degrees
Grease pie plate.
First potato layer: Potatoes slices overlapped in a circular pattern, dotted with butter, salt, pepper and fresh thyme.
Mushroom layer: Scattered mushrooms and onion strands, covered with cheese, sprinkled with pepper and thyme.
Final potato layer: Potatoes overlapped in circular pattern, sprinkled with onion strands, parmesan cheese, pepper. Dotted with butter.
Bake until potatoes are cooked through and top of pie is browned.
Check pie at 20 minutes, but could go until 45 minutes, depending on thickness of potatoes.