In a medium sauce pan, combine the sugar and water. Bring to a boil over high heat.
Add the orange wheels and reduce heat to medium-low. Simmer, stirring occasionally, for 15 minutes. Remove from heat and let cool completely.
Spray a 9" springform pan with baking spray and line the bottom with parchment paper.
Arrange the candied oranges in the prepared pan, overlapping them slightly; reserve the cooking liquid.
Make the cake:
Preheat oven to 350 degrees.
Finely grate zest from oranges and set aside.
Remove pith from and supreme the oranges. Then transfer to a food processor and pulse a few times to break up the orange segments. Set aside.
In a medium bowl, combine the flour, baking powder, salt and nutmeg, stirring with a whisk.
In the bowl of a stand mixer fitted with a paddle attachment, or in a bowl with a hand-held mixer, beat the sugar and eggs at medium speed until light and fluffy, about 5 minutes. Slowly add the olive oil and continue to beat for another minute.
Pour the batter over the candied oranges in the pan and smooth evenly with a spatula or the back of a spoon.
Bake for 45-60 minutes or until a wooden skewer or toothpick inserted into the center comes out clean.
Let cool for 30 minutes and then remove ring. Place a platter on top of the cake and quickly and carefully invert. Remove parchment paper and brush top with reserved cooking liquid.
Recipe by Two of a Kind at https://www.twoofakindcooks.com/sicilian-whole-orange-cake/