Make the pie crust

• Whisk the flour, sugar and salt in a mixing bowl.
• Cut in the cold butter until pea-sized pieces remain, then add the ice water a little at a time until the dough just holds together.
• Shape into a disc, wrap and chill until firm.

Prepare the filling

• Toss the sliced apples and cranberries with the brown sugar, cornstarch, cinnamon and lemon juice.
• Let the mixture sit so the juices start to release.

Roll out the dough

• Roll the chilled dough on a lightly floured surface into a rough round about 3 mm thick.
• Transfer it to a lined baking tray.

Fill and fold the galette

• Pile the fruit filling in the center, leaving a wide border of dough.
• Fold the border up over the fruit, pleating as you go.
• Brush the crust with the beaten egg and sprinkle with demerara sugar.

Bake the galette

• Bake in a preheated oven at 200 °C until the crust is deep golden and the juices bubble.
• Cool slightly on the tray before serving.