Line a baking tray with baking paper and place vol-au-vent cases on prepared tray and bake for 6 to 8 minutes or until crisp and then place vol-au-vents on serving plates.
Meanwhile heat oil in medium frying pan over moderate heat and add onion and garlic and cook and stir for 2 minutes or until softened and then add chicken, cook and stir for 3 to 4 minutes or until browned.
Whisk mustard, cream and cornflour in a small jug until smooth.
Add to pan, cook and stir for 2 to 3 minutes or until sauce boils and thickens.
Add asparagus to chicken mix.
Remove from heat and season and then spoon chicken mix into vol-au-vent cases and sprinkle with chives and serve with salad.