Mix together the sausage meat, onion, sage and seasoning until thoroughly combined.
Make the sausage meat into a long flat sausage shape and place on top of pastry
Using a sharp knife, cut chevrons in the pastry, starting at the end nearest to you, fold the pastry alternately over each other just like a plait. Brush the top with beaten egg.
Transfer to a baking tray and bake in the centre of the oven for 35-40 minutes, until golden brown and baked through.