Squash, Sage & Chestnut Galette

METHOD

1. Put the flour and salt into a bowl. Grate the frozen butter on a grater, then tip into the flour. Stir the butter into the flour using a table knife.
2. Add the cold water and mix briefly in the bowl with the knife to combine to a rough dough. Transfer to a lightly floured work surface and knead for a few seconds to bring the pastry together – you want to be able to see bits of raw butter in the dough but shouldn’t see any pockets of flour. Wrap the dough, and chill for 30 minutes.
3. On a lightly floured worksurface, roll the dough out to a long rectangle, about 20cm x 50cm. Press the dough and shape to create the rectangle as you roll.
4. Fold the top third of pastry over the middle third, then bring the bottom third over the top so you have a small square of three layers.
5. Spin the pastry 90 degrees and roll the pastry out to a long rectangle again, then repeat the folding in thirds. Do this again, so you fold the pastry three times in total. Then wrap the dough and chill for 30 minutes, or up to 2 days, before using.
6. To make the filling, peel, halve and deseed the squash. Chop the neck of the squash into small cubes. Tip into a saucepan with 100ml water and the garlic, and cover with a lid.
7. Cook for 15 minutes until the squash is tender when pierced with a fork. Drain any excess water, leave to steam dry for 5 minutes, then blend using a stick blender to a smooth, thick puree. Season well. Stir in the chopped sage, and a grating of nutmeg.
8. Finely slice the remaining bulb of the squash into 2mm thin slices. Tip into a bowl with the chestnuts. Drizzle in 1 tbsp oil, some seasoning and toss well.
9. Heat the oven to 200C, 180C fan/gas 6. Put a large baking sheet in the middle of the oven to heat up.
10. Roll the pastry out to a 35cm x 20cm rectangle, about 5mm thick, on a lightly floured work surface. Transfer to a large sheet of baking parchment.
11. Spoon over the squash puree and smooth over the pastry, leaving a 5cm border around the edge. Scatter over the squash slices and chestnuts, as neatly or as loosely as you like, then drizzle over any oil left in the bowl. Fold over the borders, just overlapping the filling slightly. Brush the pastry with the beaten egg.
12. Using the parchment and a board, or another baking sheet to help you, transfer the galette to the hot tray in the oven. Cook for 40-45 minutes until golden and crisp, and the squash is tender. Leave to rest for 5 minutes before serving.
13. Heat the butter in a small frying pan and add the sage leaves with a grating of nutmeg. Cook for 2-3 minutes until the sage is sizzling and crisp. Spoon the crispy sage and golden butter over the top of the galette to serve.