Mix the sugar, cornflour and gooseberries together in a bowl. Cut the pastry into 4 pieces, then roll each piece out to a rough-shaped 18 cm (7 inch) circle. Drape each piece into a buttered individual Yorkshire pudding tin, 10 cm (4 inches) in diameter and 2.5 cm (1 inch) deep, leaving the excess pastry overhanging the edges of the tins.
Spoon in the gooseberry mixture and mound up in the centre, then drizzle over the elderflower cordial. Fold the overhanging pastry up and over the filling, pleating where needed and leaving the centres of the pies open.
Brush the pastry with milk or beaten egg, sprinkle with a little sugar and bake in a preheated oven, 190°C (375°F), Gas Mark 5, for 20–25 minutes until golden. Leave to stand for 15 minutes, then loosen the edges and lift the pies out of the tins. Serve with elderflower cream (see below).