Cream the butter.
Cream in the brown sugar and ginger. Now work in the flour and the com starch. Knead the dough on an un-floured board until smooth.
Spray the shortbread pan very lightly with a non-stick vegetable oil spray. 
Firmly press the dough into the shortbread pan.
Prick the entire surface with a fork, and bake the shortbread right in the 
pan at 325° for about 30 -35 minutes, or until lightly browned. 
Let the shortbread cool in its pan for about 10 minutes before you loosen the edges with a knife and flip the pan over onto a wooden cutting board.
If the shortbread does not come right 
out, tap one edge of the pan.
Cut the shortbread into serving 
pieces while it is still warm. 
Let the pan cool before washing it in the sink or dishwasher.