Preheat the oven to 180°C (350°F) and line two baking trays with baking paper.
With an electric mixer, beat the cold butter with the brown sugar and sugar creaming them together.
There should still be clumps of butter visible.
Add the eggs and vanilla extract and beat in. Again, there should still be chunks of butter visible.
In a separate bowl, mix the flour, cornflour and baking powder together.
Add the flour mixture to the wet ingredients. The batter will be quite stiff.
Chop up the Kinder Bueno and Kinder chocolate and add that and the chocolate chips and stir in.
Divide the mixture into around 10-12 large balls and arrange on the prepared pan. Only four or five to a tray as they will spread.
I didn't roll mine, more like clumped them together in a rustic look. You want them tall balls rather than flatter balls as this will help them remain thick.
Chill the dough for 30 minutes – 1 hour to re chill the butter and avoid spreading.
Bake for around 15-20 minutes. The dough will still be a little soft to the touch.
It's at this moment you can choose to top each cookie with extra pieces of Kinder Buneo or Kinder Chocolate so that they melt into the tops of each cookie.
Video
Notes
*You can turn these into regular sized cookies. (You will end up with 20 or so cookies.)
If you do this, reduce the baki9ng time to 12-15 minutes.