Preheat the oven to 175°F.

Line two large baking pans with parchment paper and place a wire rack on top of each pan.

Slice the 3 navel oranges into thin slices, removing the ends where the slices are mostly pith.

Lay the slices out between layers of paper towels and press to absorb as much juice as possible.

Arrange the prepared orange slices on the wire racks and bake for 1 hour.

Flip the slices and bake for 1 hour.

Flip again and bake for 1 more hour for a total of 3 hours.

Check the slices after 3 hours and transfer any that are fully dried to a plate.

For any slices that still look plump or sticky, flip and return to the oven for 30 minutes.

Check again, remove slices that are done, and bake the rest for another 30 minutes, repeating until all slices are fully dried.