Make the filling by mixing the corn, coriander, spring onion, cheese and chilli with some seasoning.
Unroll the pastry sheet, roll a little thinner with a rolling pin, then use a 10cm circle cutter to cut out circles of pastry. (You should get 6 circles, then re-roll the trimmings for 2 more.) Brush edges of the circles with a little of the beaten egg, then spoon a couple of teaspoonfuls of filling mixture onto each. Fold over one half of the pastry, and seal by pinching the edge with your fingers, until you have 8 small pastyshaped empanadas. Arrange on a baking parchment lined baking sheet, brush with the rest of the egg and scatter with sesame seeds. Cover and chill for at least 30 mins before baking.
To serve, heat oven to 200C/180C fan/ gas 6 and bake for 20 mins until golden and crisp.