Using an oven or frying pan, cook the bacon in batches until fried, but not yet crispy. Set aside.
Line the base and sides of a 9x13 inch (23-35 mm) baking dish with parchment, allowing it to hang over the sides.
Peel and thinly slice the potatoes. Line the bottom of the prepared pan with two layers of the sliced potatoes. Drizzle with some of the cream, thyme leaves, Parmesan, and a small sprinkle of salt. Cover with a layer of the cooked bacon.
Top with another two layers of the potatoes. Continue layering with the cream, thyme, Parmesan, salt, then bacon and potatoes. Continue to repeat, finishing with a couple of layers of potato. Drizzle with cream, thyme, Parmesan, a little salt, and the melted butter.
Fold in the tops of the parchment paper and cover with plastic wrap. Place a slightly smaller baking pan on top and fill with something heavy such as weights or cans. Allow to rest for 20 minutes.
Preheat oven to 350˚F (180˚C). Remove the smaller pan with the weights and the plastic wrap. Cover the top with foil and bake until the potatoes are tender, about 1 hour. Remove the foil and set it aside. Bake for another 20 minutes to lightly brown the top.
Place the foil back over the casserole and top with the smaller dish and weights. Chill in the refrigerator overnight.
The next day, preheat oven to 425˚F (218˚C). Line two baking sheets with parchment.
Turn out the layered potatoes onto a large cutting board. Use a sharp knife to trim the edges. Cut the remaining casserole into small squares and skewer each top to bottom with a toothpick.
Transfer each skewer to the prepared baking sheets, on their sides and not touching. Bake in preheated oven until lightly golden, about 10 minutes. Gently flip them and bake until crisp and golden, another 10-15 minutes. Transfer to paper-towel lined plates to drain the excess oil.
Serve sprinkled with more fresh thyme and sriracha or other hot sauce if desired.