Mix together the butter and flour until a crumbly mixture forms, add the egg yolk and water. Stir well until all of the ingredients have combined. Form a ball with the pastry, cover it with clingfilm and allow it to rest in the fridge for half an hour.
Preheat the oven to 200 degrees Celsius and line a circular mold with butter and flour and then cover it with the pastry.
Place some oven paper on the pastry and pour over some dried pulses. Place in the oven and cook for 10 minutes, take the pastry out of the oven, remove the oven paper and pulses and place it back into the oven for a further 10 minutes.
After this is done, take the base of the quiche out of the oven and allow it to cool.
Reduce the oven temperature to 180 degrees Celsius.
Cook the chicken mince as per the pack instruction.
Cook the asparagus in salted boiling water and dry them with some kitchen paper.
In a pan, place the butter and onion and cook it until it browns. Remove the pan from the heat and add the mustard and cheese, stir this until it melts.
Set it aside to cool and then add the cream, eggs, chicken mince, and asparagus and stir the mixture. Distribute the stuffing on the pastry and sprinkle some black pepper on top.