Preheat the oven to 180 degrees Celsius. Prepare three baking sheets by lining them with baking parchment.
In a large bowl, mix together the butter and oil until combined. Crack the eggs in and beat the mixture until it has lightened in colour.
Tip in the flour, baking powder and baking soda. Fold together until it is all combined.
Cut the chocolate orange into 15 pieces.
Wet your hands. Use a tablespoon to scoop up some of the mixture. Press a piece of chocolate orange into it, then use your fingers to wrap the mixture around it, covering it completely. Ease the mixture off the spoon and onto one of the baking trays.
Repeat with the rest of the mixture, putting 5 cookies on each tray with plenty of space around them.
Put in the oven for 9-10 minutes until starting to colour. Remove from the oven and leave to cool on the trays.