Mix the dry ingredients: In a large bowl, combine the flour and salt. Add the cold butter cubes, tossing lightly to coat them in flour. Keep the butter pieces intact.

Combine with water: Gradually add the cold water, mixing with a knife until the dough just comes together. It should be rough, and visible chunks of butter are fine.

Form the dough: Turn the dough out onto a floured surface. Shape it into a rectangle about 20x10cm.

Roll and fold: Roll the dough into a long rectangle (about 40x15cm). Fold the top third down and the bottom third up, like a letter. Turn the dough 90 degrees and repeat the process once more. Wrap the dough in cling film and chill for 30 minutes.

Repeat and chill: Repeat the rolling, folding, and chilling process 2 more times (3 folds total). After the final fold, chill the dough for at least 1 hour before using.

Beat the softened butter until creamy using a wooden spoon or freestanding mixer. Add the caster sugar and beat thoroughly until the mixture is pale and fluffy.

In a small bowl, whisk the egg and egg yolk together. Gradually add this to the butter-sugar mixture, a tablespoon at a time, beating well after each addition.

Gently stir in the ground almonds, flaked almonds, and almond extract until evenly combined. Cover the bowl with cling film and chill in the fridge for 15-20 minutes.

Place one pastry circle on a parchment-lined baking tray and cover with cling film. Lay the second circle on top of the cling film, then chill until needed.

Fill the pastry: Remove the cling film from the pastry. Leave one pastry circle on the tray and spoon the almond filling onto it, heaping it slightly in the center and leaving a 2cm/1in border around the edge.

Add raspberries: Place the frozen raspberries in a plastic bag and use your rolling pin to break them into bits. Scatter the smashed frozen raspberries evenly over the almond filling, pressing them gently into the mixture.

Seal the galette: Brush the pastry border with some of the beaten egg, then gently lay the second pastry circle over the filling. Press the edges firmly together to seal. Use the back of a knife to ‘knock up’ the edges, then scallop the border by pushing the indentations in at 2cm/1in intervals with the knife handle.

Chill and glaze: Brush the top of the galette with beaten egg and chill in the fridge for 30 minutes.

Preheat the oven to 425F (220C)

Remove the galette from the fridge, brush with another layer of beaten egg, and score a criss-cross pattern on the surface using the tip of a knife. Make a couple of small steam holes in the center.

Bake for 25-30 minutes, or until the pastry is crisp and golden-brown.