Using a mandoline or a sharp knife, slice oranges into thin rounds (approximately ⅛ -¼" thick); discard ends.
Add water to a large pot, then bring to a boil. Add orange slices and set a timer for 3 minutes. After 3 minutes, remove the orange slices and dunk them immediately into an ice bath for 3 minutes.
Make a simple syrup by combining sugar, two cups of water, spices, and rose water (optional) in a large pot or a deep, wide pan. Bring the mixture to a boil, then simmer gently over low heat until the sugar dissolves.
Add orange slices to the syrup, then simmer gently for 45-60 minutes, or until translucent around the rinds.
Carefully remove orange slices with a slotted spoon, allowing excess syrup to drip back into the pot. Arrange on dehydrator trays, spacing evenly, and dehydrate at 135°F for 3 hours or until slightly tacky.
Arrange orange slices in a single layer on a parchment paper or wax paper-lined baking sheet. Drizzle with melted chocolate or dunk halfway into melted chocolate, then allow to dry.
Notes
If using a knife, try to keep the slices uniform in size. You should be able to get 8 to 10 slices per orange.
Make sure you use a wide pot, large enough to accommodate the oranges without overcrowding them, and stir the oranges so they can cook evenly and stay submerged in the syrup.
Although you can technically skip blanching the orange slices, this step helps to eliminate most of the bitterness from the pith (the white part of the orange).
If you don't have a dehydrator, air-dry the orange slices on a wire rack until dry, which can take anywhere from 24 to 48 hours.
If you don't dip the orange slices in chocolate, they can be stored at room temperature in an airtight container.
You can also coat the orange slices in granulated sugar, which will eliminate some of the stickiness. Or sprinkle with kosher salt once dipped in chocolate.
Use candied orange slices to decorate cakes and scones.
Candy orange slices can also be chopped and sprinkled over yogurt, ice cream, or chocolate pudding!