Preheat oven to 200 degrees Celsius (fan-forced).
Grease a 12-hole ⅓ cup capacity muffin tin and set aside until needed.
Using a ramekin or scone cutter, cut four 10cm circles from each sheet of pastry to make a total of 12 circles.
Line each of the muffin holes with one pastry circle, crinkling the pastry to fit.
Divide the corn, chopped ham and sliced spring onion equally between the muffin holes.
Pour the lightly whisked egg over the fillings.
Sprinkle the grated cheese over the top of each muffin hole.
Bake in the preheated oven for 20 minutes, or until puffed and golden.
Leave in the muffin tin for 5 minutes before eating them while warm.
If you are going to store (or freeze) the quiches after baking, transfer them to a wire rack to cool completely.