These Danish pastries are topped with dried blueberries, but any other dried fruit would be equally irresistible.
Make the dough. Put the flour, sugar, yeast and salt in the bowl of a stand mixer. Stir to combine. Rub in 15g of the butter until there are no lumps left.
Combine the milk, water and egg in a separate bowl and pour into the flour mixture. Attach the dough hook to the mixer and knead for 5 minutes on a slow speed, until you have a slightly sticky dough. Cover the bowl with cling film.
Halve the remaining butter. Place 1 half between the 2 pieces of baking paper and bash with a rolling pin until you have a rectangle about 15 x 23cm. Place in the freezer. Repeat with the second half of the butter.
Roll out the dough on a well floured worktop to a rectangle measuring roughly 30 x 60cm. Turn it so that the long side is closest to your body.
Remove the butter from the freezer. Brush away any excess flour from the surface of the dough, then place 1 piece of butter in the centre of the rectangle, short side closest to you. Fold over the right hand third of the dough so that it covers the butter.
Brush off the excess flour, then place the other butter piece on top of the folded side of dough. Fold over left-hand third of dough to enclose the butter and press down the exposed edges to seal.
Turn the dough so that the long side is closest to you and roll it out to a rectangle roughly 25 x 60cm. Brush off the excess flour.
Fold one third of the dough into the centre, then fold the other third on top, like folding an A4 letter. Wrap the dough in cling film and freeze it for 20 minutes.
Meanwhile, make the crème pâtissière. Whisk together the sugar, ginger, egg yolks, cornflour and 1 tablespoon of the milk in a medium bowl, until pale and combined.
Gently heat the remaining milk in a small pan until just boiling. Pour into the egg mixture and whisk until well combined. Return the mixture to the pan and heat gently, whisking continuously, until the mixture thickens. Pour it into a bowl, cover with cling film and set aside.
Transfer the dough to a floured worktop. With the short side closest to you, roll out to a rectangle roughly 25 x 60cm. Brush off the excess flour and fold in thirds as before. Turn the dough through 90 degrees and fold again. Re-wrap the dough in cling film and freeze again for 15 minutes.
Remove the dough from the freezer and roll it out to about 30 x 30cm square. Spread the crème pâtissière over the dough leaving a gap of a few centimetres on the side farthest away from you.
Sprinkle the dried blueberries along the gap. Start to roll the dough from the side nearest you, keeping the roll as tight as possible.
Place the baking sheet in a large proving bag, or cover with cling film, and leave the pastries to rise at room temperature for 30–45 minutes, until about doubled in size. Heat the oven to 220°C/200°C fan/425°F/Gas 7.
Bake the pastries for 18–20 minutes, until golden brown. (Cover the pastries with foil for the last 5 minutes, if they look like they are over-browning.) Brush with ginger syrup and set aside to cool on the tray.
Sift the icing sugar into a bowl and mix with the lemon juice and a drop of water to make a thick pouring consistency. Drizzle over the pastries. Leave to set.