Place the leeks, garlic and bacon into the Thermomix bowl. Chop for 4 seconds, Speed 5.
Add the butter and saute for 5 minutes, Varoma, Reverse, Speed 1 (with the MC removed but the splatter guard or rice basket on top of the lid).
Add the chopped chicken and cook for a further 5 minutes, Varoma, Reverse, Speed 1 (with the MC removed but the splatter guard or rice basket on top of the lid).
Add the cooking cream and chicken stock and cook for 20 minutes, 100 degrees, Reverse, Speed Soft (with the MC removed but the splatter guard or rice basket on top of the lid).
Add the dissolved cornflour and continue to cook for a further 2 minutes, 100 degrees, Reverse, Speed Soft (with the MC removed but the splatter guard or rice basket on top of the lid).
Cut 16 circles (4 from each sheet of pastry) from the shortcrust pastry sheets. Cut 16 slightly smaller circles (4 from each sheet) from the puff pastry. (see notes).
Place 4 of the shortcrust pastry circles onto the base of the pie maker sections. Top with chicken filling (⅔ full). Add a puff pastry circle over the top and brush lightly with the egg.
Cook until golden brown.