If you have an orange that you used just for juice, don't throw it away make candies slices :). Slice the orange and add to a pot. Sprinkle over a generous amount of sugar (2-3 tablespoons was enough for these slices) a little space of water and cook on a low simmer. Stirring occasionally until the sugar syrup thicks and most all of the liquid has evaporated.

Remove the slices from the pot and spread them out on top of a wire rack. Place a piece of parchment paper under the rack to collect any drips and allow it to completely cool and crystalize. These were left for an hour or so but the longer you leave them the more crystalized they become

Leave as it is or dice into small pieces. Decorate your cake as desired