Preheat oven to 350 °F
Peel the chop the onion, carrot, and potato, and celery into small cubes.
Place all of the vegetables and rosemary into a frying pan with the olive oil. Over medium heat, fry and stir for about 8 minutes, or until the vegetables soften and color. Add the garlic in for the last minute.
Place the vegetables in a large bowl, and allow them to cool completely.
Add the ground beef into the bowl with the vegetables. Add the salt and pepper, and 1/2 the beaten egg. Mix together.
Roll out the pastry to the size of a small towel. Place the ground beef mix along one long side, in a sausage shape. Brush the edges of the pastry with egg, then roll the pastry to cover the beef mix completely. Squeeze the ends together.
Place the roll on a baking tray and brush with the remaining egg. Bake for one hour, until golden.