Preheat the oven to 325°F.
Leaving the skin on, boil the clementines in boiling water for about 20 minutes until fully soft.
Remove from the water and, once cooled, cut in half to remove any seeds.
Add the clementines to a blender and blitz until smooth.
Add the mixture to a mixing bowl with the eggs, sugar, and lemon zest and whisk together.
Add in the olive oil and combine.
Fold in the ground almonds and baking powder.
Pour into a lined 8-inch cake tin and bake for 50 minutes until golden on top.
While the cake is baking, make the candied oranges: thinly slice the orange, then add to a pan on medium-low heat with the sugar and water. Let them simmer for 20 minutes until the oranges become soft, sticky, and sweet.
Once the cake is out of the oven, pierce it several times with a fork. Whilst it cools, make the syrup by melting the orange juice, zest, and sugar together on low heat until it forms a syrup.
Pour the syrup over the cake.
Decorate with the candied oranges and a dusting of powdered sugar.