Place the baking mixture (without the icing sugar) in a bowl. Add the butter, mix and, using your hands, quickly rub together to form a crumbly mixture.
Stir the egg yolk into the water, add and mix. Carefully fold in the raspberries. Using a small ice cream scoop, shape the mix into about 16 half-balls and place on two oven trays lined with baking paper, leaving enough space between each half-ball.
Bake for approx. 20 mins. in an oven preheated to 180 °C (convection). Remove from the oven, allow to cool on a cooling rack.
Mix the icing sugar well with the egg white and spread onto the cookies in strips.