To make the pastry, mix the flour, ground almonds, sugar and salt in a large bowl. Add the cold butter and rub it in using your fingertips until the mixture resembles fine breadcrumbs and no lumps of butter remain.
200 g (1 + ⅔ cup) plain (all-purpose) flour, 50 g (½ cup) ground almonds (almond flour), 2 Tablespoons sugar (light brown soft/caster/granulated), ½ teaspoon salt, 120 g (½ cup) vegan block butter
Gradually add enough cold water to bring the pastry together into a ball. Shape the pastry into a disc, wrap and refrigerate for at least an hour until firm enough to roll out.
1-3 Tablespoons ice cold water
Preheat the oven to 190℃/170℃ fan/375℉/gas mark 5.
Peel and core the apples then cut them into thin slices. Place the slices in a bowl and toss them with the lemon juice to coat.
3 large Bramley apples* (about 700g before peeling), juice of 1 small lemon
Stir in the sugar, cornflour, maple syrup and cinnamon, set aside while you roll out the pastry.
50 g (¼ cup) light brown soft sugar, 1 Tablespoon cornflour (cornstarch), 1 Tablespoon maple syrup, 1 teaspoon ground cinnamon
Dust a sheet of baking parchment large enough to line a large baking sheet with flour, then roll the pastry out to a roughly 30 cm/12 in circle on top of the parchment. The pastry may crack a little as you roll it, but just press the edges back together as needed – don’t worry if it looks rustic. Slide the pastry on its parchment onto the baking tray.
Sprinkle the ground almonds over the centre of the pastry, leaving a 5-7cm (2-3in) border.
3 Tablespoons ground almonds (almond flour)
Pile or arrange the apple slices on top of the almonds, letting any excess juices drip back into the bowl as you do (reserve the juice for later), and leaving the same 5-7cm border clear.
Gently fold the edges of the dough over the filling, overlapping the dough as necessary. Pinch together any cracks in the pastry. Gently brush the pastry crust with milk, then sprinkle with demerara sugar.
non-dairy milk for brushing, demerara sugar for sprinkling
Bake the galette for 1 hour until the crust is golden brown.
Once the galette is baked, pour the reserved apple juices into a small pan and cook until thick and syrupy. Add a splash of water if needed so that it is the consistency of thick syrup. Use a pastry brush to dab the syrup generously over the hot apple filling (not the crust).
Carefully slide the galette onto a wire cooling rack and allow to cool for 20-30 minutes before serving.