Roll out the pastry onto a floured board. Use pastry to line a 12-hole bun tin. Bake blind first by lining each pastry case with greaseproof paper and a little uncooked rice or unused pastry dough. Cook for 5-8 minutes at 200ºC/400ºF/Gas mark 6.
Remove the greaseproof paper and rice. Divide the onion, ham and cheese between the pastry bases.
Mix the egg and cream together and pour a little into each quiche. Return to the oven and cook at 190ºC/375ºF/Gas mark 5 for 15-20 minutes. Best served warm.