Step 1

Cut the rhubarb stalks into 3-4cm lengths. Mix in a bowl with the brown sugar, vanilla seeds and pod. Set aside.

Step 2

To make the pastry mix the flour, sugar and salt together in a large bowl. Rub in the butter until you have a sandy texture. Using a table knife, mix in the egg with 4-5 tbsp of ice-cold water, to form a rough dough. Knead very briefly until the dough comes together, then cut off one-third. Flatten each piece into a roundel about 2cm thick and wrap in clingfilm or parchment. Chill for at least 20 minutes, or for up to 1 hour.

Step 3

Line a large baking tray with baking parchment. Dust a clean surface with flour. Roll the larger pastry sheet to a rough 30cm roundel, about the thickness of a £1 coin. Transfer to the prepared tray. Scatter the ground almonds into the centre and top with the rhubarb mixture, leaving a 5cm border exposed. Discard the vanilla pod.

Step 4

Roll the smaller piece of pastry to a 23-25cm roundel and cut into 7 strips, each about 3cm wide. Lay four strips, evenly spaced, over the fruit. Working one at a time, lay the remaining 3 strips in the opposite direction, interweaving them with the other strips as you go, to create a lattice, then tucking the ends under neatly. Brush with beaten egg and scatter with demerara sugar. Chill for at least 30 minutes or freeze for 15 minutes.

Step 5

Preheat the oven to 220°C, gas mark 7. Bake the galette towards the bottom of the oven for 15 minutes. Reduce the temperature to 190°C, gas mark 5, and cook for a final 15-20 minutes until golden and the base is crisp. Rest for at least 30 minutes, before scattering with toasted flaked almonds. Serve warm or cold. Delicious with vanilla ice cream.