1.Heat oil in a medium frying pan over medium heat, cook onion and garlic, stirring, 5 minutes or until onion softens.
2.Add chicken and mushrooms, cook, stirring, until chicken changes colour. Add flour, cook, stirring, 1 minute.
3.Gradually stir in cream, cook, stirring, until mixture boils and thickens. Stir in chives, cool.
4.Preheat oven to 200°C. Oil two 12-hole (2-tablespoon/40ml) deep flat-based patty pans.
5.Cut 24 x 7cm rounds from shortcrust pastry, press into pan holes. Brush edges with a little of the egg.
6.Spoon chicken mixture into pastry cases. Cut 24 x 6cm rounds from puff pastry, top pies with puff pastry lids. Press edges firmly to seal, brush tops with remaining egg, sprinkle with sesame seeds. Cut a small slit in top of each pie.
7.Bake pies 20 minutes or until browned lightly. Stand in pan 5 minutes before serving.