Heat the oven to 350ºF (180ºC). Grease and flour a 12 serving muffin pan.
In a medium bowl, whisk together the cake flour, almond flour, baking powder, baking soda and salt. Set aside.
In a large bowl, beat the sugar, eggs, orange zest and vanilla extract together until smooth.
Gradually mix in the olive oil and beat until well combined.
Stir in the dry ingredients in two additions, alternating with the milk and orange juice. Stir just until combined. Do not over mix.
Fill the prepared muffin pan cups 2/3 full with batter. Do not overfill or cakes will be more difficult to remove.
Bake for 10-12 minutes or until the tops look light golden, but still moist and a toothpick inserted comes out clean. They bake very quickly, so check them a few minutes early to avoid over baking.
Cool the cakes in pan for 5 minutes. Remove them from pan and transfer to a cooling rack.
Brush the warm cakes with orange simple syrup and allow to cool completely.
When the cakes have cooled, dust with powdered sugar.
Orange Simple Syrup
In a small saucepan, stir together the sugar, orange juice, lemon juice, and orange zest.
Cook over low heat, stirring occasionally, just until the sugar is dissolved.