Beat butter, icing sugar and vanilla essence until light and fluffy.
Add oil and beat again.
Drop the egg and beat well.
Fold in the corn flour followed by the food colour, custard powder and cocoa powder.
Using your hand mix the flour until you achieve a soft pliable dough.
Place a small ball of dough into nozzle 9 and press with your thumb.
Bake at 160°c for 20 minutes.
