Using a serrated edge knife, cut top and bottom off of pineapple. With the pineapple set vertically on your cutting board, cut the sides off. Use a paring knife to remove any eyes that remain on the fruit.
Lay the peeled pineapple on its side and slice it into ¼ inch rounds (or even thinner if you can).
Use a paring knife or the round part of a metal frosting tip to remove the hard core center.
Lay rings in a single layer on a large baking sheet lined with parchment paper or a silicone baking mat.
Dry in 175° F oven for 8 hours while flipping pineapple rings every couple of hours.