For the pastry, put the flour and
butter in a bowl, and use your fingertips
to rub together until they resemble
breadcrumbs. Add the sugar, ground
walnuts, lemon zest and a pinch of salt,
and mix together. Add the egg yolk, then
work into the pastry to combine, until
you have a smooth dough. Wrap in cling
film and chill for at least 1 hr.
For the filling, soften the apples, sugar
and ginger in a pan for about 5 mins, then
stir in the flour but don’t cook all the way
through as it will continue to cook in the
oven. Add the Calvados and sultanas,
then leave to cool.
Heat oven to 190C/170C fan/gas 5.
Fill a large (23cm) pie dish that’s about
5cm deep with the apple mixture and
brush a little beaten egg around the
edges. On a lightly floured surface, roll
out the pastry to fit the top of the pie.
Put the lid on top and trim any excess;
trimmings can be used to decorate the
top. Use your fingers to pinch and crimp
the pastry all the way around the edge
and use the egg to glaze the top. Cut
3 little slits to let the steam out. Bake for
40-45 mins until pastry is crisp and golden.