You can make the pastry by hand, or in a food processor. If making it by hand, sieve the flour and icing sugar into a large mixing bowl from a height. Chop the butter into small cubes, then gently work the it into the flour and sugar with your fingers until the mixture resembles breadcrumbs. Beat the egg and add to the mix with the milk and gently work it together using your hands until you have a ball. Don’t work the pastry too much or it will become elastic and chewy, not crumbly and short. Sprinkle some flour over the dough and a clean work surface, and pat the ball into a thick flat round. Sprinkle over a little more flour, then wrap the pastry in clingfilm and pop it into the fridge to rest for 30 minutes. Lightly oil the inside of a 25cm non-stick loose-bottomed tart tin. Dust a clean surface and a rolling pin with flour, then carefully roll out the pastry, turning it every so often, until you've got a circle about 0.5cm thick. Roll the pastry over the rolling pin, then unroll it into the tin, making sure you push it into all the sides. Trim off any extra pastry, and use it to patch any holes, then prick the base of the case all over with a fork, cover with clingfilm, and pop it into the freezer for 30 minutes. Preheat the oven to 180ºC/350ºF/gas 4. Line the pastry case with a large piece of greaseproof paper, pushing it right into the sides. Fill the pastry case right up to the top with uncooked rice, and bake blind for 10 minutes in the preheated oven. Take the case out, carefully remove the rice (save it for baking blind another time) and greaseproof paper, and return the case to the oven to cook for a further 10 minutes, until it’s firm and almost biscuit-like. Leave to cool completely. Finely grate most of the orange zest into a bowl and whisk with 2 tablespoons of vanilla sugar and the cream until you get a silky mixture that forms soft peaks. Put half the berries into another bowl and use a fork to mash them up with the remaining tablespoon of vanilla sugar. Break up the meringue nests into rough pieces. Gently fold the mushed-up berries, and the meringue pieces, into the cream. Tip the cream mixture into the cooled tart case and gently shake it to help spread it out to the edges. Use a spatula or the back of a spoon to spread it out evenly, then sprinkle the remaining berries all over the top. Finely grate over the remaining orange zest and serve right away, with a dusting of icing sugar.