Walnut pie with caramelized apples

Sift the flour with the powdered sugar and baking powder, then mix in the salt and finely ground walnuts. Add the diced cold butter and egg yolk, then quickly knead the dough.

Divide the dough into two equal parts. Wrap one half in cling film and place it in the refrigerator. Press the other half into the bottom of a 23 cm diameter cake tin lined with baking paper. Prick it with a fork and place it in the refrigerator for 30 minutes.

Pre-bake the dough in the tin in a preheated 160°C fan oven for 15 minutes.