01 -
Get your oven hot at 450°F (230°C).
02 -
Take the skin off your potatoes and use a mandoline to cut them into thin 1/8-inch (3mm) rounds.
03 -
Warm up 3 tablespoons of melted butter in a 10-inch cast iron pan on medium heat.
04 -
Arrange potato slices in circles around the pan making two layers. Sprinkle with some salt, pepper and 1 tablespoon fresh thyme.
05 -
Moving fast, stack two more layers of potatoes, add a bit more salt and pepper and thyme, then drizzle some balsamic reduction on top.
06 -
Keep going with more potatoes, salt, pepper and thyme until halfway, then pour in three tablespoons of melted butter.
07 -
Continue with leftover potatoes, reduction, salt, pepper and thyme till you've used everything.
08 -
Push down hard with an 8-inch dinner plate or cake pan, then put the skillet in the oven for 30 minutes.
09 -
Take the hot skillet out to the stove and squish down once more with the cake pan.
10 -
Put it back in the oven and let it cook for another 25 minutes.
11 -
Let it cool a bit, then run a knife around the edges and flip onto a big plate. Cut into triangles to serve.