Preheat the
oven to 350°F/180°C/gas 4. Butter three cookie
sheets. Sift the flour, cornstarch, baking
powder, and salt into a large bowl.
Use a
wooden spoon to mix in the sugar, butter, egg,
cream, and vanilla to form a smooth dough.
Press the dough into a disk, wrap in plastic
wrap, and refrigerate for 30 minutes. Roll out
the dough on a lightly floured surface to a
thickness of 1/4 inch (5 mm).
Use a 2 1/2-inch
(6-cm) fluted cookie cutter to cut out the
cookies. Gather the dough scraps, re-roll, and
continue cutting out cookies until all the dough
is used.
Use a spatula to transfer the cookies
to the prepared cookie sheets, placing them 1
inch (2.5 cm) apart.
Bake, one sheet at a
time, for 10-15 minutes, or until just golden at
the edges. Transfer to racks and let cool.