For the filling, combine the cherries, sugar, flour, and lemon juice in a bowl and mix gently until the cherries are well-coated. You can use an olive pitter to remove the pits from cherries if you’re buying them fresh.
For the pastry, grease a 22cm pie dish and line the base with Multix Bake. Rub the butter into the flour with your fingertips until it is well combined, with no clumps, and resembles breadcrumbs. Add the caster sugar and vanilla essence, mixing well before adding the beaten egg. Mix until it forms a dough. Add a tablespoon of cold water (or less) if the mixture is too dry.
Roll into a ball, then wrap in Multix Cling and chill in the refrigerator for 20 minutes. Remove the Multix Cling and roll out about 2/3 of the pastry between two sheets of Multix Bake, until it is around 2-3 cm larger than the top of the pie dish. Remove the top sheet of the pastry and flip it into the pie dish; then, remove the other sheet.
Fill the pastry-lined dish with the cherry mixture. Roll out the remaining pastry using the same method as above, and cut it into 10 strips, approximately 3 cm wide and 25 cm long. Weave the pastry strips over the top of the pie and cut off any excess pastry around the rim of the pie tin. Pinch the edges around the rim and brush the pastry with the egg wash.
Sprinkle with the raw sugar and bake in the oven for around 35-40 minutes or until golden brown.