You will need two four-hole Yorkshire pudding tins. Preheat the oven to 200°C/180°C fan/gas mark 6, and slide a large baking sheet into the oven to get hot.
To make the pastry, first measure the flour, butter and a little salt into a food processor and whizz until the mixture resembles breadcrumbs (or place in a mixing bowl and rub the butter into the flour with your fingertips). Add the beaten egg and one tablespoon of water and mix until a ball of dough is formed.
Roll out the dough thinly, on a floured work surface, to about 3mm (⅛in) thick, then sprinkle the chopped walnuts over the pastry. Cover with a piece of clingfilm and roll over the cling film to press the nuts into the pastry. Cut out eight large circles using a pastry cutter or saucer as a guide and use to line the Yorkshire pudding tins. Place in the fridge to chill while you make the filling.
Heat the oil in a frying pan, add the shallots and cook over a high heat for two minutes, stirring frequently. Lower the heat, cover with a lid and cook for 10 minutes until soft. Add the vinegar and sugar and cook for about 15 minutes, stirring every now and then, until dark brown and caramelised. Set aside to cool.
Put the goat’s cheese, beaten eggs and one tablespoon of the parsley in a bowl, season with salt and pepper and mix until smooth.
Prick the base of the chilled tart cases all over with a fork, then spoon the shallot mixture into the pastry cases, dividing it evenly between the two tins. Pour the goat’s cheese mixture over the shallot mixture, again dividing it equally between the tins.
Slide the tins on to the hot baking sheet and cook for about 20 minutes until the pastry is crisp and the filling just set and golden. Sprinkle with the chopped parsley and serve warm or cold.
Recipe credit:Mary Berry's Absolute Favourites