Place the cheese, flours, cornstarch and salt together in a food processor and process until combined, about 30 seconds. Add the butter and process until the mixture resembles the texture of wet sand, about 20 seconds. Then add the water and pulse until large clumps of dough forms, about 10 or so pulses. Transfer the dough to a lightly floured surface and divide in half. Pat each half into a square, roughly 6". Wrap each square in plastic wrap and place into the fridge for about 45 minutes.