Preheat the oven
to 350°F/180°C/gas 4. Butter a
10 1/2 x
15 1/2-inch (26 x
36-cm) jellyroll pan.
Sift the flour, cinnamon,
ginger, and salt into a medium bowl. Beat the
butter and sugar in a large bowl with an electric
mixer at high speed until creamy.
Add the almond
extract and egg yolk, beating until just blended. Mix in the dry ingredients to form a smooth dough.
Firmly press the dough into the prepared pan to form
a smooth, even layer.
Beat the egg white and water
in a small bowl and brush it over the dough.
Sprinkle with walnuts. Score the dough into 1 -inch
(2.5-cm) diamonds.
Bake for 15-20 minutes, or
until lightly browned. Cool completely in the pan.
Cut along the lines and divide into diamonds.