Sift the
flour, baking powder, ginger, and salt into a
large bowl. Use a pastry blender to cut in the
butter until the mixture resembles fine crumbs.
Add the egg,
beating until just blended. Stir in the sugar to
form a soft dough. Turn the dough out onto a
lightly floured surface and knead until smooth.
Form the
dough into a long log 2 inches (5 cm) in
diameter, wrap in plastic wrap, and refrigerate
for at least 30 minutes.
Preheat
the oven to 375°F/190°C/gas 5. Butter three
cookie sheets. Slice the dough 1/2 inch (1 cm)
thick and place 1 inch (2.5 cm) apart on the
prepared cookie sheets.
Bake, one
sheet at a time, for 8-10 minutes, or until just
golden. Cool on the sheets until the cookies
firm slightly. Transfer to racks to finish
cooling.