Roll out the puff pastry, cut out 4 round sheets (4 x 10 cm). Line 4 pie tins with the pastry sheets.
Sauté the onions in butter. Add ground beef and fry. Stir in flour, Worcestershire sauce, water, salt and pepper and bring to the boil. Let cool down.
Pour the meat farce into the 4 tins. Cut out the lid from the remaining puff pastry, place on top and press down firmly. Pierce the lid in the middle so that the steam can escape and decorate with leftover dough if necessary. Brush with beaten egg. Place the pie tins on a parchment-lined baking sheet. Bake at 190 ° C for 20 minutes.