Cut orange in half. With a paring knife, carefully cut along the entire edge. With a spoon, scoop out the "meat" and set aside in a bowl. Repeat for all oranges. This will yield 6 empty orange halves.
Juice the orange, reserve for the cake mix.
Pre heat oven to 350°F (175°C). In a medium bowl, combine cake mix, eggs, oil and freshly squeezed orange juice. Mix until the batter has no lumps.
Place the orange cups into a muffin tin and fill with ¼ cup (60 g) of the chocolate batter.
Bake 25 minutes.
In a medium bowl, blend cream cheese, vanilla extract and orange zest until nice and smooth. Add butter and mix on medium high for a couple of minutes. Add powdered sugar and mix until the frosting is uniformly smooth. Put icing into a piping bag.
Let cup cakes cool down. Top the cakes with icing. Sprinkle extra orange zest on top for garnish.