Preheat the oven to 200C/180C Fan/Gas 6. Grease a 23cm/9in (4cm/2in deep) loose-bottomed tart tin with butter. Roll out the pastry on a lightly floured work surface to a thickness of 5mm/Â¼in. Wrap the pastry around your rolling pin and gently lower it into the prepared tin, pressing the pastry gently into the base and sides.
Cover the pastry case with cling film or baking parchment, then fill with baking beans, uncooked rice or flour. Bake in the oven for 20-25 minutes. Remove the lining paper and baking beads.
Brush the inside of the tart all over with the beaten egg. Return the pastry case to the oven for a further 5 minutes, or until golden-brown. Remove the pastry case from the oven.
Reduce the oven temperature to 180C/160C Fan/Gas 4.
In a bowl, whisk 8 eggs and the cream together, then season with salt and freshly ground black pepper.
Arrange the asparagus spears inside the tart case, then sprinkle over the chicken pieces and marjoram. Pour over the egg and cream mixture until almost level with the top of the pastry case. Scatter the ComtÃ© on top.
Bake the quiche for 20-25 minutes, or until the filling has set and the pastry is golden-brown. Remove from the oven and set aside on a wire rack to cool slightly.
To serve, cut the quiche into slices and serve with the salad leaves.