These pretty shortcakes are perfectly dainty for perching on a saucer with a cup of tea. Using an impression mat and finishing with delicate icing makes them look like little doilies.
Sift the flour into a large mixing bowl, add the salt and the chilled, cubed butter. Cut the butter into the flour using round-bladed knife until the butter pieces are half their original size.
Using your hands, rub the butter into the flour, until the mixture resembles fine breadcrumbs. Add the icing sugar and mix to combine.
Make a well in the centre, add the rose water and egg yolks and, using the round-bladed knife, mix to combine. Then, using your hands, gently knead and gather the mixture into a smooth ball, flatten into a disc, cover and chill for at least 1 hour.
Lightly dust the work surface with flour and, using a rolling pin, roll out the chilled dough until 3–4mm thick. Use the cutter to stamp out as many shapes as you can (re-roll the trimming as necessary), one by one laying each round on the silicone mat and gently rolling it again to flatten it to 1mm thick and form an impression. Then, carefully peel each biscuit shape off the mat and use the cutter to stamp it out again into a neat circle.
Arrange the rounds on the lined baking sheets and chill for 20 minutes. Meanwhile, heat the oven to 180°C/160°C fan/Gas 4.
Bake the biscuits for about 12 minutes, until firm and starting to turn golden brown at the edges. Remove from the oven and leave to cool on the baking sheets.
When the biscuits are cold, spray the top of each with silver or pearl lustre spray and set aside.
Prepare the icing. Whisk the egg white in a stand mixer fitted with the whisk, until foamy, then gradually add the icing sugar, whisking continuously until incorporated. Add the glucose and lemon juice and continue mixing until the icing is shiny and will hold a soft peak.
Spoon half the icing into a piping bag fitted with a fine writing nozzle and use the food-colouring paste to tint the remaining half pale blue. Spoon this into the other piping bag.
Pipe small dots of icing in alternate colours around the edge of each biscuit and delicate flower shapes in the middle. Leave to dry for at least 30 minutes before serving.