Lightly butter a 9 by 13 inch baking pan.
Dissolve the instant espresso in the vanilla. Set aside.
In a medium bowl combine the flour, cornstarch, cardamom and salt. Whisk and set aside.
Add the flour mixture and beat until well combined, stopping to scrape the bottom and sides of the bowl once.
Transfer dough into pan and spread dough pressing lightly to ensure it is evenly distributed into the pan.
Before baking, evenly cut the dough (cutting all the way-through) into 40 cookie bars. Evenly prick each cookie with a fork 3 times.
Bake, turning the pan once after 15 minutes. Continue baking until top is dry and lightly golden about 30 minutes.
Remove cookies from oven and cool in pan on wire rack for a few minutes and using a small knife re-cut the cookies along the lines. Let the cookies cool before removing them from pan.
Cookies can be stored at room temperature up to 5 days. Cookies can also be stored in the freezer for later consumption.